From 1e1c187be724392bce9ced29c33ba46179c88dfc Mon Sep 17 00:00:00 2001 From: YamiDoesDev Date: Fri, 4 Nov 2022 16:13:30 +0000 Subject: [PATCH] deploy: 3774abd5aa83fb157ee5516d55865276fb6ff494 --- 02_basics.html | 154 +++++++++++++---- 02_basics.md | 66 ++++---- 04_introduction_to_objects.html | 104 +++++++++++- 04_introduction_to_objects.md | 20 +++ 05_types_of_objects.html | 84 +++++----- 05_types_of_objects.md | 87 +++++----- print_page.html | 282 ++++++++++++++++++++++++-------- search/search_index.js | 2 +- sitemap.xml | 14 +- sitemap.xml.gz | Bin 199 -> 200 bytes 10 files changed, 584 insertions(+), 229 deletions(-) diff --git a/02_basics.html b/02_basics.html index 3d1ed40..33d5840 100644 --- a/02_basics.html +++ b/02_basics.html @@ -965,10 +965,10 @@
  1. Nutzung der Konsole
  2. Primitive Datentypen
    3. -
  3. Nicht Primitive Datentypen
    4. -
  4. Operatoren
    5. -
  5. Bedingungen
    6. -
  6. Schleifen
    7. +
  7. Nicht Primitive Datentypen
    8. +
  8. Operatoren
    9. +
  9. Bedingungen
    10. +
  10. Schleifen
  11. Exceptions

Nutzung der Konsole

@@ -1083,17 +1083,53 @@ vergleichbar mit einem char-Array.

String concatString = "hello" + "World"; System.out.println("concatString: " + concatString); -

Methoden der Standardbibliothek: -

myString.charAt(); // Returns the char value at the specified index.
-myString.indexOf(); // Returns the index within this string of the first occurrence of the specified substring.
-myString.substring(); // Returns a string that is a substring of this string.
-myString.equals(); // Compares this string to the specified object.
-myString.toLowerCase(); // Converts all of the characters in this String to lower case.
-myString.toUpperCase(); // Converts all of the characters in this String to upper case.
-myString.contains(); // Returns true if and only if this string contains the specified sequence of char values.
-myString.replaceAll(); // Replaces each substring of this string that matches the given regular expression with the given replacement.
-myString.compareTo(); // Compares two strings lexicographically. The comparison is based on the Unicode value of each character in the strings.
-

+

Methoden der Standardbibliothek:

+ + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + +
MethodeBeschreibung
myString.charAt()Returns the char value at the specified index.
myString.indexOf()Returns the index within this string of the first occurrence of the specified substring.
myString.substring()Returns a string that is a substring of this string.
myString.equals()Compares this string to the specified object.
myString.toLowerCase()Converts all of the characters in this String to lower case.
myString.toUpperCase()Converts all of the characters in this String to upper case.
myString.contains()Returns true if and only if this string contains the specified sequence of char values.
myString.replaceAll()Replaces each substring of this string that matches the given regular expression with the given replacement.
myString.compareTo()Compares two strings lexicographically. The comparison is based on the Unicode value of each character in the strings.

Numeric Datatypes

Im Gegensatz zu den primitiven Datentypen werden hier "Wrapper" verwendet, um dynamisch mit den Werten arbeiten zu können. Das erlaubt auch die Erweiterung @@ -1111,14 +1147,41 @@ um verschiedene Methoden in der Standardbibliothek.

Float myFloat = (float)10.0; myFloat.isNaN(); // Returns true if this Float value is a Not-a-Number (NaN), false otherwise

-

Funktionen für alle Numerischen Datentypen (Nicht Primitiv): -

myNumber.compareTo(); // Compares two Integer objects numerically.
-myNumber.toString(); // Returns a String object representing this Integer's value.
-myNumber.intValue(); // Returns the value of this Integer as an int.
-myNumber.floatValue(); // Returns the value of this Integer as a float after a widening primitive conversion.
-myNumber.doubleValue(); // Returns the value of this Integer as a double after a widening primitive conversion.
-myNumber.shortValue(); // Returns the value of this Integer as a short after a narrowing primitive conversion.
-

+

Funktionen für alle Numerischen Datentypen (Nicht Primitiv):

+ + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + +
MethodeBeschreibung
myNumber.compareTo()Compares two Integer objects numerically.
myNumber.toString()Returns a String object representing this Integer's value.
myNumber.intValue()Returns the value of this Integer as an int.
myNumber.floatValue()Returns the value of this Integer as a float after a widening primitive conversion.
myNumber.doubleValue()Returns the value of this Integer as a double after a widening primitive conversion.
myNumber.shortValue()Returns the value of this Integer as a short after a narrowing primitive conversion.

Arrays

Bei Arrays handelt es sich um Schleifen eines bestimmten Datentypen. Sie werden verwendet, um mehrere Werte in einer Variable zu speichern.

@@ -1154,14 +1217,41 @@ verwendet, um mehrere Werte in einer Variable zu speichern.

System.out.println("]"); }

-

Methoden: -

Arrays.toString(myArray); // a string representation of the object.
-Arrays.copyOf(myArray, 3); // Copies the specified array, truncating or padding with zeros (if necessary) so the copy has the specified length.
-Arrays.compare(myArray, myArray); // Compares two int arrays lexicographically.
-Arrays.equals(myArray, myArray); // Returns true if the two specified arrays of ints are equal to one another.
-Arrays.sort(myArray); // Sorts the specified array into ascending numerical order
-Arrays.fill(myArray, 0); // Assigns the specified int value to each element of the specified array of ints.
-

+

Methoden:

+ + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + +
MethodeBeschreibung
Arrays.toString(Array a)a string representation of the object.
Arrays.copyOf(Array a, int index)Copies the specified array, truncating or padding with zeros (if necessary) so the copy has the specified length.
Arrays.compare(Array a, Array b)Compares two int arrays lexicographically.
Arrays.equals(Array a, Array b)Returns true if the two specified arrays of ints are equal to one another.
Arrays.sort(Array a)Sorts the specified array into ascending numerical order
Arrays.fill(Array a, int number)Assigns the specified int value to each element of the specified array of ints.

Operatoren

Arithmetic Operators

int calcAddition = 20 + 10; // = 30
@@ -1347,7 +1437,7 @@ verwendet, um mehrere Werte in einer Variable zu speichern.

   
     
       Letztes Update:
-      November 2, 2022 20:46:05
+      November 4, 2022 16:13:00
       
         

         Erstellt:
diff --git a/02_basics.md b/02_basics.md
index 1d833ce..18611de 100644
--- a/02_basics.md
+++ b/02_basics.md
@@ -3,10 +3,10 @@
 ## Table of Contents
 1. [Nutzung der Konsole](#nutzung-der-konsole)
 2. [Primitive Datentypen](#primitive-datentypen)
-3. [Nicht Primitive Datentypen](#)
-4. [Operatoren](#)
-5. [Bedingungen](#)
-6. [Schleifen](#)
+3. [Nicht Primitive Datentypen](#nicht-primitive-datentypen)
+4. [Operatoren](#operatoren)
+5. [Bedingungen](#bedingungen)
+6. [Schleifen](#schleifen)
 7. [Exceptions](#exceptions)
 
 ## Nutzung der Konsole
@@ -108,17 +108,18 @@ System.out.println("concatString: " + concatString);
 ```
 
 Methoden der Standardbibliothek:
-```java
-myString.charAt(); // Returns the char value at the specified index.
-myString.indexOf(); // Returns the index within this string of the first occurrence of the specified substring.
-myString.substring(); // Returns a string that is a substring of this string.
-myString.equals(); // Compares this string to the specified object.
-myString.toLowerCase(); // Converts all of the characters in this String to lower case.
-myString.toUpperCase(); // Converts all of the characters in this String to upper case.
-myString.contains(); // Returns true if and only if this string contains the specified sequence of char values.
-myString.replaceAll(); // Replaces each substring of this string that matches the given regular expression with the given replacement.
-myString.compareTo(); // Compares two strings lexicographically. The comparison is based on the Unicode value of each character in the strings.
-```
+
+| Methode                | Beschreibung                                                                                                            |
+|------------------------|-------------------------------------------------------------------------------------------------------------------------|
+| myString.charAt()      | Returns the char value at the specified index.                                                                          |
+| myString.indexOf()     | Returns the index within this string of the first occurrence of the specified substring.                                |
+| myString.substring()   | Returns a string that is a substring of this string.                                                                    |
+| myString.equals()      | Compares this string to the specified object.                                                                           |
+| myString.toLowerCase() | Converts all of the characters in this String to lower case.                                                            |
+| myString.toUpperCase() | Converts all of the characters in this String to upper case.                                                            |
+| myString.contains()    | Returns true if and only if this string contains the specified sequence of char values.                                 |
+| myString.replaceAll()  | Replaces each substring of this string that matches the given regular expression with the given replacement.            |
+| myString.compareTo()   |  Compares two strings lexicographically. The comparison is based on the Unicode value of each character in the strings. |
 
 ### Numeric Datatypes
 
@@ -144,14 +145,16 @@ myFloat.isNaN(); // Returns true if this Float value is a Not-a-Number (NaN), fa
 ```
 
 Funktionen für alle Numerischen Datentypen (Nicht Primitiv):
-```java
-myNumber.compareTo(); // Compares two Integer objects numerically.
-myNumber.toString(); // Returns a String object representing this Integer's value.
-myNumber.intValue(); // Returns the value of this Integer as an int.
-myNumber.floatValue(); // Returns the value of this Integer as a float after a widening primitive conversion.
-myNumber.doubleValue(); // Returns the value of this Integer as a double after a widening primitive conversion.
-myNumber.shortValue(); // Returns the value of this Integer as a short after a narrowing primitive conversion.
-```
+
+| Methode                | Beschreibung                                                                          |
+|------------------------|---------------------------------------------------------------------------------------|
+| myNumber.compareTo()   | Compares two Integer objects numerically.                                             |
+| myNumber.toString()    | Returns a String object representing this Integer's value.                            |                              
+| myNumber.intValue()    | Returns the value of this Integer as an int.                                          |                                           
+| myNumber.floatValue()  | Returns the value of this Integer as a float after a widening primitive conversion.   |   
+| myNumber.doubleValue() | Returns the value of this Integer as a double after a widening primitive conversion.  |
+| myNumber.shortValue()  | Returns the value of this Integer as a short after a narrowing primitive conversion.  |  
+
 
 ### Arrays
 Bei Arrays handelt es sich um Schleifen eines bestimmten Datentypen. Sie werden
@@ -194,14 +197,15 @@ for(int row = 0; row < my2DArray.length; row++) {
 ```
 
 Methoden:
-```java
-Arrays.toString(myArray); // a string representation of the object.
-Arrays.copyOf(myArray, 3); // Copies the specified array, truncating or padding with zeros (if necessary) so the copy has the specified length.
-Arrays.compare(myArray, myArray); // Compares two int arrays lexicographically.
-Arrays.equals(myArray, myArray); // Returns true if the two specified arrays of ints are equal to one another.
-Arrays.sort(myArray); // Sorts the specified array into ascending numerical order
-Arrays.fill(myArray, 0); // Assigns the specified int value to each element of the specified array of ints.
-```
+
+| Methode                           | Beschreibung                                                                                                      |
+|-----------------------------------|-------------------------------------------------------------------------------------------------------------------|
+| Arrays.toString(Array a)          | a string representation of the object.                                                                            |                                                                           
+| Arrays.copyOf(Array a, int index) | Copies the specified array, truncating or padding with zeros (if necessary) so the copy has the specified length. | 
+| Arrays.compare(Array a, Array b)  | Compares two int arrays lexicographically.                                                                        |                                                                        
+| Arrays.equals(Array a, Array b)   | Returns true if the two specified arrays of ints are equal to one another.                                        |                                        
+| Arrays.sort(Array a)              | Sorts the specified array into ascending numerical order                                                          |                                                         
+| Arrays.fill(Array a, int number)  | Assigns the specified int value to each element of the specified array of ints.                                   |                                   
 
 ## Operatoren
 
diff --git a/04_introduction_to_objects.html b/04_introduction_to_objects.html
index c8a9c16..3020f53 100644
--- a/04_introduction_to_objects.html
+++ b/04_introduction_to_objects.html
@@ -364,6 +364,33 @@
       
     
   
+
+      
+        
  • 
+  
+    Modifier
+  
+  
+    
+  
 
    • 
       
         
  • 
@@ -498,6 +525,33 @@
       
     
   
+
    • 
+      
+        
  • 
+  
+    Modifier
+  
+  
+    
+  
 
    • 
       
         
  • 
@@ -566,6 +620,54 @@ The term simply means the creation of a new object, i.e. an instance, from a cla
 
    String name = new String("Thomas");
 
    
 
+
    Modifier
    
+
    Quelle: w3schools.com
    
+
    Access-Modifier
    
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
    ModifierBeschreibung
    publicThe code is accessible for all classes
    privateThe code is only accessible within the declared class
    protectedThe code is accessible in the same package and subclasses.
    defaultThe code is only accessible in the same package. This is used when you don't specify a modifier.
    
+
    Non-Access-Modifier
    
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
    ModifierBeschreibung
    finalThe class cannot be inherited by other classes
    abstractThe class cannot be used to create objects (To access an abstract class, it must be inherited from another class.
    
 
    #1 Einfache Objekte und Veerbung
    
 
    Lernziele:
 * eine Klasse erzeugen 
@@ -819,7 +921,7 @@ The term simply means the creation of a new object, i.e. an instance, from a cla
   
     
       Letztes Update:
-      November 2, 2022 20:46:05
+      November 4, 2022 16:13:00
       
         
    
         Erstellt:
diff --git a/04_introduction_to_objects.md b/04_introduction_to_objects.md
index 12a7fe8..046e9b6 100644
--- a/04_introduction_to_objects.md
+++ b/04_introduction_to_objects.md
@@ -27,6 +27,26 @@ int nbr = 5;
 String name = new String("Thomas");
 ```
 
+## Modifier
+
+Quelle: [w3schools.com](https://www.w3schools.com/java/java_modifiers.asp)
+
+### Access-Modifier
+
+| Modifier  | Beschreibung                                                                                     |
+|-----------|--------------------------------------------------------------------------------------------------|
+| public    | The code is accessible for all classes                                                           |
+| private   | The code is only accessible within the declared class                                            |
+| protected | The code is accessible in the same package and subclasses.                                       |
+| default   | The code is only accessible in the same package. This is used when you don't specify a modifier. |
+
+### Non-Access-Modifier
+
+| Modifier | Beschreibung                                                                                                      |
+|----------|-------------------------------------------------------------------------------------------------------------------|
+| final    | The class cannot be inherited by other classes                                                                    |
+| abstract | The class cannot be used to create objects (To access an abstract class, it must be inherited from another class. |
+
 
 ## #1 Einfache Objekte und Veerbung
 **Lernziele:**
diff --git a/05_types_of_objects.html b/05_types_of_objects.html
index e159cda..2a76b7f 100644
--- a/05_types_of_objects.html
+++ b/05_types_of_objects.html
@@ -638,52 +638,14 @@
     }
 }
    • -

    Abstract and Interface

    -

    // Regex.java
-public interface Regex {
-    public String concatStrings(String left, String right);
-}
-
    -
    // Main.java
-abstract class Language {
-    public void showLanguage() {
-        System.out.println("This text is presented to you by Java");
-    }
-    public abstract void sayHelloWorld();
-}
-
-// Main.java
-public class Main extends Language implements Regex {
-    public static void main(String[] args) {
-        // Language myLanguage = new Language();
-        // 'Language' is abstract; cannot be instantiated
-
-        Main myObject = new Main();
-        myObject.sayHelloWorld();
-
-        String wortwitz = myObject.concatStrings("du", "schlampe");
-        System.out.println(wortwitz); // duschlampe
-    }
-
-    @Override
-    public void sayHelloWorld() {
-        System.out.println("I refuse to say that!");
-    }
-
-    @Override
-    public String concatStrings(String left, String right) {
-        return left + right;
-    }
-}
-
    // SaveState.java
 
 import java.security.InvalidParameterException;
 
 public class SaveState<T> implements Comparable<SaveState> {
-    private T saveEntry;
-    private int saveID = 0;
-    private static int staticSaveID;
+private T saveEntry;
+private int saveID = 0;
+private static int staticSaveID;
 
     // constructor
     SaveState(T saveEntry) throws InvalidParameterException {
@@ -727,6 +689,44 @@
         return 0;
     }
 }
+
    +

    Abstract and Interface

    +

    // Regex.java
+public interface Regex {
+    public String concatStrings(String left, String right);
+}
+
    +
    // Main.java
+abstract class Language {
+    public void showLanguage() {
+        System.out.println("This text is presented to you by Java");
+    }
+    public abstract void sayHelloWorld();
+}
+
+// Main.java
+public class Main extends Language implements Regex {
+    public static void main(String[] args) {
+        // Language myLanguage = new Language();
+        // 'Language' is abstract; cannot be instantiated
+
+        Main myObject = new Main();
+        myObject.sayHelloWorld();
+
+        String wortwitz = myObject.concatStrings("du", "schlampe");
+        System.out.println(wortwitz); // duschlampe
+    }
+
+    @Override
+    public void sayHelloWorld() {
+        System.out.println("I refuse to say that!");
+    }
+
+    @Override
+    public String concatStrings(String left, String right) {
+        return left + right;
+    }
+}

    Collections

    import java.util.*;
@@ -969,7 +969,7 @@
   
     
       Letztes Update:
-      November 2, 2022 20:46:05
+      November 4, 2022 16:13:00
       
         
    
         Erstellt:
diff --git a/05_types_of_objects.md b/05_types_of_objects.md
index 22e6896..a1567c6 100644
--- a/05_types_of_objects.md
+++ b/05_types_of_objects.md
@@ -65,55 +65,15 @@ public class Main /*extends Language implements Regex*/ {
 }
 ```
 
-### Abstract and Interface
-```java
-// Regex.java
-public interface Regex {
-    public String concatStrings(String left, String right);
-}
-```
-```java
-// Main.java
-abstract class Language {
-    public void showLanguage() {
-        System.out.println("This text is presented to you by Java");
-    }
-    public abstract void sayHelloWorld();
-}
-
-// Main.java
-public class Main extends Language implements Regex {
-    public static void main(String[] args) {
-        // Language myLanguage = new Language();
-        // 'Language' is abstract; cannot be instantiated
-
-        Main myObject = new Main();
-        myObject.sayHelloWorld();
-
-        String wortwitz = myObject.concatStrings("du", "schlampe");
-        System.out.println(wortwitz); // duschlampe
-    }
-
-    @Override
-    public void sayHelloWorld() {
-        System.out.println("I refuse to say that!");
-    }
-
-    @Override
-    public String concatStrings(String left, String right) {
-        return left + right;
-    }
-}
-```
 ```java
 // SaveState.java
 
 import java.security.InvalidParameterException;
 
 public class SaveState implements Comparable {
-    private T saveEntry;
-    private int saveID = 0;
-    private static int staticSaveID;
+private T saveEntry;
+private int saveID = 0;
+private static int staticSaveID;
 
     // constructor
     SaveState(T saveEntry) throws InvalidParameterException {
@@ -159,6 +119,47 @@ public class SaveState implements Comparable {
 }
 ```
 
+### Abstract and Interface
+```java
+// Regex.java
+public interface Regex {
+    public String concatStrings(String left, String right);
+}
+```
+```java
+// Main.java
+abstract class Language {
+    public void showLanguage() {
+        System.out.println("This text is presented to you by Java");
+    }
+    public abstract void sayHelloWorld();
+}
+
+// Main.java
+public class Main extends Language implements Regex {
+    public static void main(String[] args) {
+        // Language myLanguage = new Language();
+        // 'Language' is abstract; cannot be instantiated
+
+        Main myObject = new Main();
+        myObject.sayHelloWorld();
+
+        String wortwitz = myObject.concatStrings("du", "schlampe");
+        System.out.println(wortwitz); // duschlampe
+    }
+
+    @Override
+    public void sayHelloWorld() {
+        System.out.println("I refuse to say that!");
+    }
+
+    @Override
+    public String concatStrings(String left, String right) {
+        return left + right;
+    }
+}
+```
+
 ## Collections
 
 ```java
diff --git a/print_page.html b/print_page.html
index 997ab3f..64a70c7 100644
--- a/print_page.html
+++ b/print_page.html
@@ -588,10 +588,10 @@ Hello, World!
 
      
 
    1. Nutzung der Konsole
      2. 
 
    2. Primitive Datentypen
      3. 
-
    3. Nicht Primitive Datentypen
      4. 
-
    4. Operatoren
      5. 
-
    5. Bedingungen
      6. 
-
    6. Schleifen
      7. 
+
    7. Nicht Primitive Datentypen
      8. 
+
    8. Operatoren
      9. 
+
    9. Bedingungen
      10. 
+
    10. Schleifen
      11. 
 
    11. Exceptions
      12. 
 
    
 
    Nutzung der Konsole
    
@@ -706,17 +706,53 @@ vergleichbar mit einem char-Array.
    
 String concatString = "hello" + "World";
 System.out.println("concatString: " + concatString);
    -

    Methoden der Standardbibliothek: -

    myString.charAt(); // Returns the char value at the specified index.
-myString.indexOf(); // Returns the index within this string of the first occurrence of the specified substring.
-myString.substring(); // Returns a string that is a substring of this string.
-myString.equals(); // Compares this string to the specified object.
-myString.toLowerCase(); // Converts all of the characters in this String to lower case.
-myString.toUpperCase(); // Converts all of the characters in this String to upper case.
-myString.contains(); // Returns true if and only if this string contains the specified sequence of char values.
-myString.replaceAll(); // Replaces each substring of this string that matches the given regular expression with the given replacement.
-myString.compareTo(); // Compares two strings lexicographically. The comparison is based on the Unicode value of each character in the strings.
-

    +

    Methoden der Standardbibliothek:

    + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + +
    MethodeBeschreibung
    myString.charAt()Returns the char value at the specified index.
    myString.indexOf()Returns the index within this string of the first occurrence of the specified substring.
    myString.substring()Returns a string that is a substring of this string.
    myString.equals()Compares this string to the specified object.
    myString.toLowerCase()Converts all of the characters in this String to lower case.
    myString.toUpperCase()Converts all of the characters in this String to upper case.
    myString.contains()Returns true if and only if this string contains the specified sequence of char values.
    myString.replaceAll()Replaces each substring of this string that matches the given regular expression with the given replacement.
    myString.compareTo()Compares two strings lexicographically. The comparison is based on the Unicode value of each character in the strings.

    Numeric Datatypes

    Im Gegensatz zu den primitiven Datentypen werden hier "Wrapper" verwendet, um dynamisch mit den Werten arbeiten zu können. Das erlaubt auch die Erweiterung @@ -734,14 +770,41 @@ um verschiedene Methoden in der Standardbibliothek.

    Float myFloat = (float)10.0; myFloat.isNaN(); // Returns true if this Float value is a Not-a-Number (NaN), false otherwise

    -

    Funktionen für alle Numerischen Datentypen (Nicht Primitiv): -

    myNumber.compareTo(); // Compares two Integer objects numerically.
-myNumber.toString(); // Returns a String object representing this Integer's value.
-myNumber.intValue(); // Returns the value of this Integer as an int.
-myNumber.floatValue(); // Returns the value of this Integer as a float after a widening primitive conversion.
-myNumber.doubleValue(); // Returns the value of this Integer as a double after a widening primitive conversion.
-myNumber.shortValue(); // Returns the value of this Integer as a short after a narrowing primitive conversion.
-

    +

    Funktionen für alle Numerischen Datentypen (Nicht Primitiv):

    + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + +
    MethodeBeschreibung
    myNumber.compareTo()Compares two Integer objects numerically.
    myNumber.toString()Returns a String object representing this Integer's value.
    myNumber.intValue()Returns the value of this Integer as an int.
    myNumber.floatValue()Returns the value of this Integer as a float after a widening primitive conversion.
    myNumber.doubleValue()Returns the value of this Integer as a double after a widening primitive conversion.
    myNumber.shortValue()Returns the value of this Integer as a short after a narrowing primitive conversion.

    Arrays

    Bei Arrays handelt es sich um Schleifen eines bestimmten Datentypen. Sie werden verwendet, um mehrere Werte in einer Variable zu speichern.

    @@ -777,14 +840,41 @@ verwendet, um mehrere Werte in einer Variable zu speichern.

    System.out.println("]"); }

    -

    Methoden: -

    Arrays.toString(myArray); // a string representation of the object.
-Arrays.copyOf(myArray, 3); // Copies the specified array, truncating or padding with zeros (if necessary) so the copy has the specified length.
-Arrays.compare(myArray, myArray); // Compares two int arrays lexicographically.
-Arrays.equals(myArray, myArray); // Returns true if the two specified arrays of ints are equal to one another.
-Arrays.sort(myArray); // Sorts the specified array into ascending numerical order
-Arrays.fill(myArray, 0); // Assigns the specified int value to each element of the specified array of ints.
-

    +

    Methoden:

    + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + +
    MethodeBeschreibung
    Arrays.toString(Array a)a string representation of the object.
    Arrays.copyOf(Array a, int index)Copies the specified array, truncating or padding with zeros (if necessary) so the copy has the specified length.
    Arrays.compare(Array a, Array b)Compares two int arrays lexicographically.
    Arrays.equals(Array a, Array b)Returns true if the two specified arrays of ints are equal to one another.
    Arrays.sort(Array a)Sorts the specified array into ascending numerical order
    Arrays.fill(Array a, int number)Assigns the specified int value to each element of the specified array of ints.

    Operatoren

    Arithmetic Operators

    int calcAddition = 20 + 10; // = 30
@@ -1069,6 +1159,54 @@ The term simply means the creation of a new object, i.e. an instance, from a cla
 
    String name = new String("Thomas");
 
    
 
+
    Modifier
    
+
    Quelle: w3schools.com
    
+
    Access-Modifier
    
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    ModifierBeschreibung
    publicThe code is accessible for all classes
    privateThe code is only accessible within the declared class
    protectedThe code is accessible in the same package and subclasses.
    defaultThe code is only accessible in the same package. This is used when you don't specify a modifier.
    
+
    Non-Access-Modifier
    
+
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    ModifierBeschreibung
    finalThe class cannot be inherited by other classes
    abstractThe class cannot be used to create objects (To access an abstract class, it must be inherited from another class.
    
 
    #1 Einfache Objekte und Veerbung
    
 
    Lernziele:
 * eine Klasse erzeugen 
@@ -1373,52 +1511,14 @@ The term simply means the creation of a new object, i.e. an instance, from a cla
     }
 }
    -

    Abstract and Interface

    -

    // Regex.java
-public interface Regex {
-    public String concatStrings(String left, String right);
-}
-
    -
    // Main.java
-abstract class Language {
-    public void showLanguage() {
-        System.out.println("This text is presented to you by Java");
-    }
-    public abstract void sayHelloWorld();
-}
-
-// Main.java
-public class Main extends Language implements Regex {
-    public static void main(String[] args) {
-        // Language myLanguage = new Language();
-        // 'Language' is abstract; cannot be instantiated
-
-        Main myObject = new Main();
-        myObject.sayHelloWorld();
-
-        String wortwitz = myObject.concatStrings("du", "schlampe");
-        System.out.println(wortwitz); // duschlampe
-    }
-
-    @Override
-    public void sayHelloWorld() {
-        System.out.println("I refuse to say that!");
-    }
-
-    @Override
-    public String concatStrings(String left, String right) {
-        return left + right;
-    }
-}
-
    // SaveState.java
 
 import java.security.InvalidParameterException;
 
 public class SaveState<T> implements Comparable<SaveState> {
-    private T saveEntry;
-    private int saveID = 0;
-    private static int staticSaveID;
+private T saveEntry;
+private int saveID = 0;
+private static int staticSaveID;
 
     // constructor
     SaveState(T saveEntry) throws InvalidParameterException {
@@ -1462,6 +1562,44 @@ The term simply means the creation of a new object, i.e. an instance, from a cla
         return 0;
     }
 }
+
    +

    Abstract and Interface

    +

    // Regex.java
+public interface Regex {
+    public String concatStrings(String left, String right);
+}
+
    +
    // Main.java
+abstract class Language {
+    public void showLanguage() {
+        System.out.println("This text is presented to you by Java");
+    }
+    public abstract void sayHelloWorld();
+}
+
+// Main.java
+public class Main extends Language implements Regex {
+    public static void main(String[] args) {
+        // Language myLanguage = new Language();
+        // 'Language' is abstract; cannot be instantiated
+
+        Main myObject = new Main();
+        myObject.sayHelloWorld();
+
+        String wortwitz = myObject.concatStrings("du", "schlampe");
+        System.out.println(wortwitz); // duschlampe
+    }
+
+    @Override
+    public void sayHelloWorld() {
+        System.out.println("I refuse to say that!");
+    }
+
+    @Override
+    public String concatStrings(String left, String right) {
+        return left + right;
+    }
+}

    Collections

    import java.util.*;
diff --git a/search/search_index.js b/search/search_index.js
index 61a80a2..4aaf80d 100644
--- a/search/search_index.js
+++ b/search/search_index.js
@@ -1 +1 @@
-const local_index = {"config":{"indexing":"full","lang":["de"],"min_search_length":3,"prebuild_index":false,"separator":"[\\s\\-]+"},"docs":[{"location":"index.html","text":"Crashkurs Java im Modul Algorithmen und Datenstrukturen public class Main { public static void main ( String [] args ) { System . out . println ( \"Die Seite ist noch leer\" ); } }","title":"Crashkurs Java im Modul Algorithmen und Datenstrukturen"},{"location":"index.html#crashkurs-java-im-modul-algorithmen-und-datenstrukturen","text":"public class Main { public static void main ( String [] args ) { System . out . println ( \"Die Seite ist noch leer\" ); } }","title":"Crashkurs Java im Modul Algorithmen und Datenstrukturen"},{"location":"01_hello_world.html","text":"01: Hello World Approach 1: Simple String Output // main.java public class main { public static void main ( String [] args ) { System . out . println ( \"Hello, World!\" ); } } >> javac main.java >> java main Hello, World! Was sagt dieser Code nun aus? * Eine Klasse \"main\" ist \u00f6ffentlich * Dem Compiler wird die statische Methode main vorlegt * Diese wird bei jedem Java Code genutzt * Wir rufen die Klasse System auf und f\u00fchren einen println -Befehl aus * Hello, World! wird in der Konsole ausgegeben Approach 2: Using Console Arguments // main.java public class main { public static void main ( String [] args ) { System . out . println ( args [ 0 ] + \" \" + args [ 1 ] ); } } >> javac main.java >> java main Hello, World! Hello, World! Was ist nun anders? * Die Main-Methode \u00fcbergibt standardm\u00e4\u00dfig Konsolenargumente als Array vom Typ String mit dem Namen args * Jedes Argument hat einen Index im Array * F\u00fcr 2 Argumente rufen wir die ersten zwei Indexes auf, beginnend bei 0","title":"01: Hello World"},{"location":"01_hello_world.html#01-hello-world","text":"","title":"01: Hello World"},{"location":"01_hello_world.html#approach-1-simple-string-output","text":"// main.java public class main { public static void main ( String [] args ) { System . out . println ( \"Hello, World!\" ); } } >> javac main.java >> java main Hello, World! Was sagt dieser Code nun aus? * Eine Klasse \"main\" ist \u00f6ffentlich * Dem Compiler wird die statische Methode main vorlegt * Diese wird bei jedem Java Code genutzt * Wir rufen die Klasse System auf und f\u00fchren einen println -Befehl aus * Hello, World! wird in der Konsole ausgegeben","title":"Approach 1: Simple String Output"},{"location":"01_hello_world.html#approach-2-using-console-arguments","text":"// main.java public class main { public static void main ( String [] args ) { System . out . println ( args [ 0 ] + \" \" + args [ 1 ] ); } } >> javac main.java >> java main Hello, World! Hello, World! Was ist nun anders? * Die Main-Methode \u00fcbergibt standardm\u00e4\u00dfig Konsolenargumente als Array vom Typ String mit dem Namen args * Jedes Argument hat einen Index im Array * F\u00fcr 2 Argumente rufen wir die ersten zwei Indexes auf, beginnend bei 0","title":"Approach 2: Using Console Arguments"},{"location":"02_basics.html","text":"02: Basics Table of Contents Nutzung der Konsole Primitive Datentypen Nicht Primitive Datentypen Operatoren Bedingungen Schleifen Exceptions Nutzung der Konsole Ausgabe System . out . println ( \"print me and create a new line\" ); System . out . println (); // prints nothing but creates new line afterwards System . out . print ( \"print me without a new line | \" ); System . out . print ( \"print me but add a new line \\n\" ); System . out . print ( \"yeah, this is on the new line! \\n\" ); System . out . println (); // prints nothing but creates new line afterwards // https://www.digitalocean.com/community/tutorials/java-printf-method System . out . printf ( \"%s %s \\n\" , \"parameter 1\" , \"parameter 2\" ); System . out . printf ( \"%s %e %f\" , \"10.50\" , 10.50 , 10.50 ); Eingabe import java.util.Scanner ; // class and method : start Scanner myScanner = new Scanner ( System . in ); System . out . print ( \"Enter Username: \" ); String username = myScanner . nextLine (); System . out . print ( \"Enter Password: \" ); String password = myScanner . nextLine (); System . out . println ( \"your Username: \" + username + \"\\nyour password: \" + password ); // class and method : end Primitive Datentypen Quelle: w3schools.com Data Type Size Description byte 1 byte Stores whole numbers from -128 to 127 short 2 bytes Stores whole numbers from -32,768 to 32,767 int 4 bytes Stores whole numbers from -2,147,483,648 to 2,147,483,647 long 8 bytes Stores whole numbers from -9,223,372,036,854,775,808 to 9,223,372,036,854,775,807 float 4 bytes Stores fractional numbers. Sufficient for storing 6 to 7 decimal digits double 8 bytes Stores fractional numbers. Sufficient for storing 15 decimal digits boolean 1 bit Stores true or false values char 2 bytes Stores a single character/letter or ASCII values Type Casting Bei Type Casting handelt es sich um das \u00fcberf\u00fchren eines primitiven Datentypen in einen anderen. Quelle: w3schools.com Widening Casting (automatically) Hier wird ein kleinerer Typ in einen gr\u00f6\u00dferen Typ konvertiert byte -> short -> char -> int -> long -> float -> double int myInt = 9 ; double myDouble = myInt ; // Automatic casting: int to double System . out . println ( myInt ); // Outputs 9 System . out . println ( myDouble ); // Outputs 9.0 Narrowing Casting (manually) Hier wird ein gr\u00f6\u00dferer Typ in einen kleineren Typ konvertiert double -> float -> long -> int -> char -> short -> byte double myDouble = 9.78d ; int myInt = ( int ) myDouble ; // Manual casting: double to int System . out . println ( myDouble ); // Outputs 9.78 System . out . println ( myInt ); // Outputs 9 Nicht Primitive Datentypen String String ist eine Wrapperklasse, welche eine Zeichenkette aus einzelnen chars zusammenbaut. In manchen Programmiersprachen (z.B. C++) ist ein String vergleichbar mit einem char-Array. String myString = \"this is a text\" ; System . out . println ( \"myString: \" + myString ); String concatString = \"hello\" + \"World\" ; System . out . println ( \"concatString: \" + concatString ); Methoden der Standardbibliothek: myString . charAt (); // Returns the char value at the specified index. myString . indexOf (); // Returns the index within this string of the first occurrence of the specified substring. myString . substring (); // Returns a string that is a substring of this string. myString . equals (); // Compares this string to the specified object. myString . toLowerCase (); // Converts all of the characters in this String to lower case. myString . toUpperCase (); // Converts all of the characters in this String to upper case. myString . contains (); // Returns true if and only if this string contains the specified sequence of char values. myString . replaceAll (); // Replaces each substring of this string that matches the given regular expression with the given replacement. myString . compareTo (); // Compares two strings lexicographically. The comparison is based on the Unicode value of each character in the strings. Numeric Datatypes Im Gegensatz zu den primitiven Datentypen werden hier \"Wrapper\" verwendet, um dynamisch mit den Werten arbeiten zu k\u00f6nnen. Das erlaubt auch die Erweiterung um verschiedene Methoden in der Standardbibliothek. Integer: Integer myNumber = 10 ; Integer . parseInt (); // Parses the string argument as a signed decimal integer. Integer . parseUnsignedInt (); // Parses the string argument as an unsigned decimal integer. Integer . valueOf (); // Returns an Integer object holding the value of the specified String. Float and Double: Double myDouble = 10.0 ; myDouble . isNaN (); // Returns true if this Double value is a Not-a-Number (NaN), false otherwise. Float myFloat = ( float ) 10.0 ; myFloat . isNaN (); // Returns true if this Float value is a Not-a-Number (NaN), false otherwise Funktionen f\u00fcr alle Numerischen Datentypen (Nicht Primitiv): myNumber . compareTo (); // Compares two Integer objects numerically. myNumber . toString (); // Returns a String object representing this Integer's value. myNumber . intValue (); // Returns the value of this Integer as an int. myNumber . floatValue (); // Returns the value of this Integer as a float after a widening primitive conversion. myNumber . doubleValue (); // Returns the value of this Integer as a double after a widening primitive conversion. myNumber . shortValue (); // Returns the value of this Integer as a short after a narrowing primitive conversion. Arrays Bei Arrays handelt es sich um Schleifen eines bestimmten Datentypen. Sie werden verwendet, um mehrere Werte in einer Variable zu speichern. String [] myStringArray = new String [ 3 ] ; myStringArray [ 0 ] = \"ROT\" ; myStringArray [ 1 ] = \"GR\u00dcN\" ; myStringArray [ 2 ] = \"BLAU\" ; int [] myIntArray = { 0 , 1 , 2 }; System . out . println ( myIntArray . length ); // 3 System . out . println ( Arrays . toString ( myIntArray )); // [0,1,2] multidimensionale Arrays: int [][] my2DArray = { { 1 , 2 }, { 3 , 4 , 5 }, { 6 , 7 , 8 , 9 }, }; System . out . println ( my2DArray . length ); System . out . println ( my2DArray [ 0 ] . length ); for ( int row = 0 ; row < my2DArray . length ; row ++ ) { System . out . print ( \"[\" ); for ( int column = 0 ; column < my2DArray [ row ] . length ; column ++ ) { if ( column == ( my2DArray [ row ] . length - 1 ) ) { System . out . print ( my2DArray [ row ][ column ] ); continue ; } System . out . print ( my2DArray [ row ][ column ] + \", \" ); } System . out . println ( \"]\" ); } Methoden: Arrays . toString ( myArray ); // a string representation of the object. Arrays . copyOf ( myArray , 3 ); // Copies the specified array, truncating or padding with zeros (if necessary) so the copy has the specified length. Arrays . compare ( myArray , myArray ); // Compares two int arrays lexicographically. Arrays . equals ( myArray , myArray ); // Returns true if the two specified arrays of ints are equal to one another. Arrays . sort ( myArray ); // Sorts the specified array into ascending numerical order Arrays . fill ( myArray , 0 ); // Assigns the specified int value to each element of the specified array of ints. Operatoren Arithmetic Operators int calcAddition = 20 + 10 ; // = 30 int calcSubstraction = 20 - 10 ; // = 10 int calcMultiplication = 20 * 10 ; // = 200 int calcDivision = 20 / 10 ; // = 2 int calcModulus = 20 % 3 ; // = 2 int myNumber = 10 ; myNumber ++ ; // myNumber = 11 myNumber -- ; // myNumber = 10 myNumber -- ; // myNumber = 9 Comparison Operators int biggerNumber = 20 ; int biggerNumberAgain = 20 ; int smallerNumber = 10 ; // (20 == 20) => true // (20 != 20) => false // (20 > 10) => true // (20 < 10) => false // (20 >= 10) => true // (20 >= 10) => true Bedingungen wir verwenden folgende Variablen: int biggerNumber = 20 ; int biggerNumberAgain = 20 ; int smallerNumber = 10 ; if-condition (better version) if ( biggerNumber > smallerNumber ) { System . out . println ( \"the left number is bigger!\" ); } if-condition (worse version) // prefer to not write it down like this! if ( biggerNumber == biggerNumberAgain ) System . out . println ( \"We don't do this here...\" ); if-else-condition if ( biggerNumber < smallerNumber ) { System . out . println ( \"the left number is smaller!\" ); } else if ( biggerNumber < biggerNumberAgain ) { System . out . println ( \"but this time, the left number is smaller!\" ); } else { System . out . println ( \"the left number is just too big!\" ); } switch-case int luckyNumber = 69 ; switch ( luckyNumber ) { case 13 : System . out . println ( \"some people consider 13 to be a lucky number\" ); break ; // we need this to avoid default! case 7 : System . out . println ( \"slot machines value this number high\" ); break ; // we need this to avoid default! default : System . out . println ( \"seems, your number was not lucky enough...\" ); } Schleifen while-loop int whileNumber = 3 ; while ( whileNumber > 0 ) { System . out . println ( whileNumber ); whileNumber -- ; } do-while-loop System . out . println ( \"--- doWhileNumber:\" ); int doWhileNumber = 3 ; do { System . out . println ( doWhileNumber ); doWhileNumber -- ; } while ( doWhileNumber > 0 ); for-loop System . out . println ( \"--- forNumber:\" ); for ( int iterator = 0 ; iterator <= 5 ; iterator ++ ) { System . out . println ( iterator ); } Beispiel Ausf\u00fchrung int myNumber = 1 ; // count, how many times we can add 2 until we reach 16, // but we pretend, 13 doesn't exist for reasons for ( int counter = 0 ; counter <= 10 ; counter ++ ) { myNumber += 2 ; if ( myNumber == 13 ) { continue ; } System . out . println ( counter ); if ( myNumber >= 16 ) { break ; } } Hinweis Vermeidet einfache Variablennamen wie i, u, usw.m um die Lesbarkeit einfach zu halten // for ( int i = 0 ; i < 10 ; i ++ ) { for ( int u = 30 ; i > 15 ; u ++ ) { myArray [ u ][ i ] = i + u ; } } for-each-loop arrays int [] myArray = { 1 , 2 , 3 }; for ( int selectedValue : myArray ) { System . out . println ( \"myArray: \" + selectedValue ); selectedValue = 0 ; } System . out . println ( Arrays . toString ( myArray )); for ( int selection : myArray ) { System . out . println ( selection ); } lists LinkedList < String > myLinkedList = new LinkedList <> (); myLinkedList . add ( \"List_1\" ); myLinkedList . add ( \"List_2\" ); myLinkedList . add ( \"List_3\" ); for ( int selectedValue : myArray ) { System . out . println ( selectedValue ); } maps HashMap < Integer , String > myHashMap = new HashMap <> (); myHashMap . put ( 1 , \"Larry\" ); myHashMap . put ( 2 , \"Steve\" ); myHashMap . put ( 3 , \"James\" ); myHashMap . forEach (( key , value ) -> { System . out . println ( key + \" \" + value ); }); Exceptions public class Main { public static void main ( String [] args ) { // simple exception handling try { int [] myNumbers = { 1 , 2 , 3 }; System . out . println ( myNumbers [ 10 ] ); } catch ( Exception exception ) { System . out . println ( exception ); System . out . println ( \"---\" ); } // extended exception handling try { int [] myNumbers = { 1 , 2 , 3 }; printTenthIndex ( myNumbers ); } catch ( RuntimeException exception ) { System . out . println ( \"class: \" + exception . getClass ()); // class: class java.lang.RuntimeException System . out . println ( \"cause: \" + exception . getCause ()); // cause: java.lang.RuntimeException: array is not big enough System . out . println ( \"message: \" + exception . getMessage ()); // message: index was not found } finally { System . out . println ( \"finally! The 'try catch' is finished.\" ); } } public static void printTenthIndex ( int [] array ) throws RuntimeException { Exception r = new RuntimeException ( \"array is not big enough\" ); // not every exception supports causes if ( array . length < 11 ) { throw new RuntimeException ( \"index was not found\" , r ); } System . out . println ( array [ 10 ] ); } }","title":"02: Basics"},{"location":"02_basics.html#02-basics","text":"","title":"02: Basics"},{"location":"02_basics.html#table-of-contents","text":"Nutzung der Konsole Primitive Datentypen Nicht Primitive Datentypen Operatoren Bedingungen Schleifen Exceptions","title":"Table of Contents"},{"location":"02_basics.html#nutzung-der-konsole","text":"","title":"Nutzung der Konsole"},{"location":"02_basics.html#ausgabe","text":"System . out . println ( \"print me and create a new line\" ); System . out . println (); // prints nothing but creates new line afterwards System . out . print ( \"print me without a new line | \" ); System . out . print ( \"print me but add a new line \\n\" ); System . out . print ( \"yeah, this is on the new line! \\n\" ); System . out . println (); // prints nothing but creates new line afterwards // https://www.digitalocean.com/community/tutorials/java-printf-method System . out . printf ( \"%s %s \\n\" , \"parameter 1\" , \"parameter 2\" ); System . out . printf ( \"%s %e %f\" , \"10.50\" , 10.50 , 10.50 );","title":"Ausgabe"},{"location":"02_basics.html#eingabe","text":"import java.util.Scanner ; // class and method : start Scanner myScanner = new Scanner ( System . in ); System . out . print ( \"Enter Username: \" ); String username = myScanner . nextLine (); System . out . print ( \"Enter Password: \" ); String password = myScanner . nextLine (); System . out . println ( \"your Username: \" + username + \"\\nyour password: \" + password ); // class and method : end","title":"Eingabe"},{"location":"02_basics.html#primitive-datentypen","text":"Quelle: w3schools.com Data Type Size Description byte 1 byte Stores whole numbers from -128 to 127 short 2 bytes Stores whole numbers from -32,768 to 32,767 int 4 bytes Stores whole numbers from -2,147,483,648 to 2,147,483,647 long 8 bytes Stores whole numbers from -9,223,372,036,854,775,808 to 9,223,372,036,854,775,807 float 4 bytes Stores fractional numbers. Sufficient for storing 6 to 7 decimal digits double 8 bytes Stores fractional numbers. Sufficient for storing 15 decimal digits boolean 1 bit Stores true or false values char 2 bytes Stores a single character/letter or ASCII values","title":"Primitive Datentypen"},{"location":"02_basics.html#type-casting","text":"Bei Type Casting handelt es sich um das \u00fcberf\u00fchren eines primitiven Datentypen in einen anderen. Quelle: w3schools.com","title":"Type Casting"},{"location":"02_basics.html#widening-casting-automatically","text":"Hier wird ein kleinerer Typ in einen gr\u00f6\u00dferen Typ konvertiert byte -> short -> char -> int -> long -> float -> double int myInt = 9 ; double myDouble = myInt ; // Automatic casting: int to double System . out . println ( myInt ); // Outputs 9 System . out . println ( myDouble ); // Outputs 9.0","title":"Widening Casting (automatically)"},{"location":"02_basics.html#narrowing-casting-manually","text":"Hier wird ein gr\u00f6\u00dferer Typ in einen kleineren Typ konvertiert double -> float -> long -> int -> char -> short -> byte double myDouble = 9.78d ; int myInt = ( int ) myDouble ; // Manual casting: double to int System . out . println ( myDouble ); // Outputs 9.78 System . out . println ( myInt ); // Outputs 9","title":"Narrowing Casting (manually)"},{"location":"02_basics.html#nicht-primitive-datentypen","text":"","title":"Nicht Primitive Datentypen"},{"location":"02_basics.html#string","text":"String ist eine Wrapperklasse, welche eine Zeichenkette aus einzelnen chars zusammenbaut. In manchen Programmiersprachen (z.B. C++) ist ein String vergleichbar mit einem char-Array. String myString = \"this is a text\" ; System . out . println ( \"myString: \" + myString ); String concatString = \"hello\" + \"World\" ; System . out . println ( \"concatString: \" + concatString ); Methoden der Standardbibliothek: myString . charAt (); // Returns the char value at the specified index. myString . indexOf (); // Returns the index within this string of the first occurrence of the specified substring. myString . substring (); // Returns a string that is a substring of this string. myString . equals (); // Compares this string to the specified object. myString . toLowerCase (); // Converts all of the characters in this String to lower case. myString . toUpperCase (); // Converts all of the characters in this String to upper case. myString . contains (); // Returns true if and only if this string contains the specified sequence of char values. myString . replaceAll (); // Replaces each substring of this string that matches the given regular expression with the given replacement. myString . compareTo (); // Compares two strings lexicographically. The comparison is based on the Unicode value of each character in the strings.","title":"String"},{"location":"02_basics.html#numeric-datatypes","text":"Im Gegensatz zu den primitiven Datentypen werden hier \"Wrapper\" verwendet, um dynamisch mit den Werten arbeiten zu k\u00f6nnen. Das erlaubt auch die Erweiterung um verschiedene Methoden in der Standardbibliothek. Integer: Integer myNumber = 10 ; Integer . parseInt (); // Parses the string argument as a signed decimal integer. Integer . parseUnsignedInt (); // Parses the string argument as an unsigned decimal integer. Integer . valueOf (); // Returns an Integer object holding the value of the specified String. Float and Double: Double myDouble = 10.0 ; myDouble . isNaN (); // Returns true if this Double value is a Not-a-Number (NaN), false otherwise. Float myFloat = ( float ) 10.0 ; myFloat . isNaN (); // Returns true if this Float value is a Not-a-Number (NaN), false otherwise Funktionen f\u00fcr alle Numerischen Datentypen (Nicht Primitiv): myNumber . compareTo (); // Compares two Integer objects numerically. myNumber . toString (); // Returns a String object representing this Integer's value. myNumber . intValue (); // Returns the value of this Integer as an int. myNumber . floatValue (); // Returns the value of this Integer as a float after a widening primitive conversion. myNumber . doubleValue (); // Returns the value of this Integer as a double after a widening primitive conversion. myNumber . shortValue (); // Returns the value of this Integer as a short after a narrowing primitive conversion.","title":"Numeric Datatypes"},{"location":"02_basics.html#arrays","text":"Bei Arrays handelt es sich um Schleifen eines bestimmten Datentypen. Sie werden verwendet, um mehrere Werte in einer Variable zu speichern. String [] myStringArray = new String [ 3 ] ; myStringArray [ 0 ] = \"ROT\" ; myStringArray [ 1 ] = \"GR\u00dcN\" ; myStringArray [ 2 ] = \"BLAU\" ; int [] myIntArray = { 0 , 1 , 2 }; System . out . println ( myIntArray . length ); // 3 System . out . println ( Arrays . toString ( myIntArray )); // [0,1,2] multidimensionale Arrays: int [][] my2DArray = { { 1 , 2 }, { 3 , 4 , 5 }, { 6 , 7 , 8 , 9 }, }; System . out . println ( my2DArray . length ); System . out . println ( my2DArray [ 0 ] . length ); for ( int row = 0 ; row < my2DArray . length ; row ++ ) { System . out . print ( \"[\" ); for ( int column = 0 ; column < my2DArray [ row ] . length ; column ++ ) { if ( column == ( my2DArray [ row ] . length - 1 ) ) { System . out . print ( my2DArray [ row ][ column ] ); continue ; } System . out . print ( my2DArray [ row ][ column ] + \", \" ); } System . out . println ( \"]\" ); } Methoden: Arrays . toString ( myArray ); // a string representation of the object. Arrays . copyOf ( myArray , 3 ); // Copies the specified array, truncating or padding with zeros (if necessary) so the copy has the specified length. Arrays . compare ( myArray , myArray ); // Compares two int arrays lexicographically. Arrays . equals ( myArray , myArray ); // Returns true if the two specified arrays of ints are equal to one another. Arrays . sort ( myArray ); // Sorts the specified array into ascending numerical order Arrays . fill ( myArray , 0 ); // Assigns the specified int value to each element of the specified array of ints.","title":"Arrays"},{"location":"02_basics.html#operatoren","text":"","title":"Operatoren"},{"location":"02_basics.html#arithmetic-operators","text":"int calcAddition = 20 + 10 ; // = 30 int calcSubstraction = 20 - 10 ; // = 10 int calcMultiplication = 20 * 10 ; // = 200 int calcDivision = 20 / 10 ; // = 2 int calcModulus = 20 % 3 ; // = 2 int myNumber = 10 ; myNumber ++ ; // myNumber = 11 myNumber -- ; // myNumber = 10 myNumber -- ; // myNumber = 9","title":"Arithmetic Operators"},{"location":"02_basics.html#comparison-operators","text":"int biggerNumber = 20 ; int biggerNumberAgain = 20 ; int smallerNumber = 10 ; // (20 == 20) => true // (20 != 20) => false // (20 > 10) => true // (20 < 10) => false // (20 >= 10) => true // (20 >= 10) => true","title":"Comparison Operators"},{"location":"02_basics.html#bedingungen","text":"wir verwenden folgende Variablen: int biggerNumber = 20 ; int biggerNumberAgain = 20 ; int smallerNumber = 10 ;","title":"Bedingungen"},{"location":"02_basics.html#if-condition-better-version","text":"if ( biggerNumber > smallerNumber ) { System . out . println ( \"the left number is bigger!\" ); }","title":"if-condition (better version)"},{"location":"02_basics.html#if-condition-worse-version","text":"// prefer to not write it down like this! if ( biggerNumber == biggerNumberAgain ) System . out . println ( \"We don't do this here...\" );","title":"if-condition (worse version)"},{"location":"02_basics.html#if-else-condition","text":"if ( biggerNumber < smallerNumber ) { System . out . println ( \"the left number is smaller!\" ); } else if ( biggerNumber < biggerNumberAgain ) { System . out . println ( \"but this time, the left number is smaller!\" ); } else { System . out . println ( \"the left number is just too big!\" ); }","title":"if-else-condition"},{"location":"02_basics.html#switch-case","text":"int luckyNumber = 69 ; switch ( luckyNumber ) { case 13 : System . out . println ( \"some people consider 13 to be a lucky number\" ); break ; // we need this to avoid default! case 7 : System . out . println ( \"slot machines value this number high\" ); break ; // we need this to avoid default! default : System . out . println ( \"seems, your number was not lucky enough...\" ); }","title":"switch-case"},{"location":"02_basics.html#schleifen","text":"","title":"Schleifen"},{"location":"02_basics.html#while-loop","text":"int whileNumber = 3 ; while ( whileNumber > 0 ) { System . out . println ( whileNumber ); whileNumber -- ; }","title":"while-loop"},{"location":"02_basics.html#do-while-loop","text":"System . out . println ( \"--- doWhileNumber:\" ); int doWhileNumber = 3 ; do { System . out . println ( doWhileNumber ); doWhileNumber -- ; } while ( doWhileNumber > 0 );","title":"do-while-loop"},{"location":"02_basics.html#for-loop","text":"System . out . println ( \"--- forNumber:\" ); for ( int iterator = 0 ; iterator <= 5 ; iterator ++ ) { System . out . println ( iterator ); }","title":"for-loop"},{"location":"02_basics.html#beispiel-ausfuhrung","text":"int myNumber = 1 ; // count, how many times we can add 2 until we reach 16, // but we pretend, 13 doesn't exist for reasons for ( int counter = 0 ; counter <= 10 ; counter ++ ) { myNumber += 2 ; if ( myNumber == 13 ) { continue ; } System . out . println ( counter ); if ( myNumber >= 16 ) { break ; } }","title":"Beispiel Ausf\u00fchrung"},{"location":"02_basics.html#hinweis","text":"Vermeidet einfache Variablennamen wie i, u, usw.m um die Lesbarkeit einfach zu halten // for ( int i = 0 ; i < 10 ; i ++ ) { for ( int u = 30 ; i > 15 ; u ++ ) { myArray [ u ][ i ] = i + u ; } }","title":"Hinweis"},{"location":"02_basics.html#for-each-loop","text":"","title":"for-each-loop"},{"location":"02_basics.html#arrays_1","text":"int [] myArray = { 1 , 2 , 3 }; for ( int selectedValue : myArray ) { System . out . println ( \"myArray: \" + selectedValue ); selectedValue = 0 ; } System . out . println ( Arrays . toString ( myArray )); for ( int selection : myArray ) { System . out . println ( selection ); }","title":"arrays"},{"location":"02_basics.html#lists","text":"LinkedList < String > myLinkedList = new LinkedList <> (); myLinkedList . add ( \"List_1\" ); myLinkedList . add ( \"List_2\" ); myLinkedList . add ( \"List_3\" ); for ( int selectedValue : myArray ) { System . out . println ( selectedValue ); }","title":"lists"},{"location":"02_basics.html#maps","text":"HashMap < Integer , String > myHashMap = new HashMap <> (); myHashMap . put ( 1 , \"Larry\" ); myHashMap . put ( 2 , \"Steve\" ); myHashMap . put ( 3 , \"James\" ); myHashMap . forEach (( key , value ) -> { System . out . println ( key + \" \" + value ); });","title":"maps"},{"location":"02_basics.html#exceptions","text":"public class Main { public static void main ( String [] args ) { // simple exception handling try { int [] myNumbers = { 1 , 2 , 3 }; System . out . println ( myNumbers [ 10 ] ); } catch ( Exception exception ) { System . out . println ( exception ); System . out . println ( \"---\" ); } // extended exception handling try { int [] myNumbers = { 1 , 2 , 3 }; printTenthIndex ( myNumbers ); } catch ( RuntimeException exception ) { System . out . println ( \"class: \" + exception . getClass ()); // class: class java.lang.RuntimeException System . out . println ( \"cause: \" + exception . getCause ()); // cause: java.lang.RuntimeException: array is not big enough System . out . println ( \"message: \" + exception . getMessage ()); // message: index was not found } finally { System . out . println ( \"finally! The 'try catch' is finished.\" ); } } public static void printTenthIndex ( int [] array ) throws RuntimeException { Exception r = new RuntimeException ( \"array is not big enough\" ); // not every exception supports causes if ( array . length < 11 ) { throw new RuntimeException ( \"index was not found\" , r ); } System . out . println ( array [ 10 ] ); } }","title":"Exceptions"},{"location":"03_coding_style.html","text":"03: Coding Style Programme k\u00f6nnen sehr schnell sehr komplex werden. Daher ist es wichtig, sich an Stil-Regeln zu halten, um sie m\u00f6glichst verst\u00e4ndlich zu schreiben. 1. Selbsterkl\u00e4rend Code sollte sich so gut wie m\u00f6glich selbst erkl\u00e4ren. Dazu sind sprechende Variablen-, Funktions-, Klassennamen etc. erforderlich. Kurze Namen sind nur in kleinen G\u00fcltigkeitsbereichen oder bei klarer Bedeutung (z.B. i f\u00fcr for-Schleifen Iteratoren, y f\u00fcr vertikale Position) erlaubt. 1.1 Kommentare Kommentare sind in diesem Zusammenhang vorallem zur Strukturierung/Abgrenzung des Codes empfohlen, und um die Verst\u00e4ndlichkeit zu erh\u00f6hen. Kommentare sollten nicht das Offensichtliche wiederholen (siehe Bild). Selbstverst\u00e4ndlich kann Code zum besseren eigenen Verst\u00e4ndnis kommentiert werden. Denken Sie aber daran, dass bei Code \u00c4nderungen auch die Kommentare mit gepflegt werden m\u00fcssen. 4. Benennung Die folgenden Regelungen sind empfohlen und in keinster Weise verpflichtend. 4.1 camelCase f\u00fcr Variablen und Funktionen Variablen- und Funktionsnamen beginnen mit Kleinbuchstaben und folgen der camelCase Notation, d.h. bei zusammengesetzten Namen beginnen die Wortteile im Inneren mit einem Gro\u00dfbuchstaben. Funktionsnamen beschreiben dabei eine Aktivit\u00e4t ( z.B. calculateHorizontalPosition() ) oder eine Frage (z.B. isHit() ). Gleiches gilt f\u00fcr Attribute und Methoden. 4.2 Unterstrich vor formalen Parametern Formale Parameter folgen dem Variablen-Benennungs-Schema, mit dem Zusatz eines Unterstriches am Anfang. (z.B. moveTo(_x: number, _y: number) ). 4.3 PascalCase f\u00fcr Klassen und Interfaces Die Namen von Klassen und Interfaces beginnen mit einem Gro\u00dfbuchstaben und folgen sonst der Kamelnotation (also PascalCase). Klassen und Interfaces beschreiben im Normalfall ein bestimmtes Objekt, nicht eine Gruppe von Objekten. Dies sollte sich im Namen wiederspiegeln ( Produkt statt Produkte ). 4.4 Gro\u00dfschreibung f\u00fcr Enumeratoren Die Namen von Enumerationen und deren Elemente werden durchgehend mit Gro\u00dfbuchstaben geschreiben. Wortteile werden bei Bedarf mit Unterstrich getrennt. 5. Doppelte und einfache Anf\u00fchrungszeichen Es empfielt sich, einfache Anf\u00fchrungszeichen ' ' f\u00fcr char und doppelte Anf\u00fchrungszeichen \" \" f\u00fcr Strings zu verwenden. 6. Formatierung Code ist sinnvoll Formatiert mit Einsch\u00fcben etc. Im Regelfall unterst\u00fctzt VSCode dies Automatisch. Machen Sie Gebrauch von der automatischen Formatierungsfunktion. Anleitung f\u00fcr IntelliJ Anleitung f\u00fcr Visual Studio Code Anleitung f\u00fcr Eclipse 8. \"Magische\" Zahlen Der Gebrauch von \"magischen\" Zahlen sollte vermieden werden. Solange es nicht extrem offensichtlich ist, wof\u00fcr eine Zahl steht (z.B. Math.pow(x, 5) ), sollte eine Variable (nach den oben genannten Guidelines) angelegt werden, welcher die Zahl als Wert zugewiesen wird. So entsteht der Zusammenhang zwischen der Variablen und ihrer Bedeutung, und der Wert kann an einer zentralen Stelle angepasst werden. 9. Dateinamen und -aufteilung Dateinamen d\u00fcrfen keine Leerzeichen oder Umlaute enthalten, sind sonst aber frei w\u00e4hlbar (s.u. f\u00fcr Einschr\u00e4nkungen). Es wird empfohlen, die Zeichenwahl auf a-z, A-Z, 0-9 und _ zu beschr\u00e4nken. Code kann auf mehrere Dateien aufgeteilt werden, sofern dies sinnvoll erscheint (z.B. um eine Trennung von Funktion und Daten zu erreichen). Wenn Klassen verwendet werden, sollte jede ihre eigene Datei bekommen. Sofern eine Datei eine bestimmte Klasse enth\u00e4lt, soll die Datei mit dem Namen der Klasse benannt sein. 10. Wiederholungen sind schlecht Code der sich ohne oder nur mit minimalen \u00c4nderungen wiederholt, kann in den allermeisten F\u00e4llen besser geschrieben werden, z.B. \u00fcber eine Funktion mit \u00dcbergabeparametern, oder indem man nur den ge\u00e4nderten Teil implementiert oder \u00fcberschreibt, w\u00e4hrend der Rest f\u00fcr alles gleich generiert wird. Dies hat viele Vorteile: Es macht den Code generell \u00fcbersichtlicher (und damit besser verst\u00e4ndlich), k\u00fcrzer, und wartungsfreundlicher.","title":"03: Coding Style"},{"location":"03_coding_style.html#03-coding-style","text":"Programme k\u00f6nnen sehr schnell sehr komplex werden. Daher ist es wichtig, sich an Stil-Regeln zu halten, um sie m\u00f6glichst verst\u00e4ndlich zu schreiben.","title":"03: Coding Style"},{"location":"03_coding_style.html#1-selbsterklarend","text":"Code sollte sich so gut wie m\u00f6glich selbst erkl\u00e4ren. Dazu sind sprechende Variablen-, Funktions-, Klassennamen etc. erforderlich. Kurze Namen sind nur in kleinen G\u00fcltigkeitsbereichen oder bei klarer Bedeutung (z.B. i f\u00fcr for-Schleifen Iteratoren, y f\u00fcr vertikale Position) erlaubt.","title":"1. Selbsterkl\u00e4rend"},{"location":"03_coding_style.html#11-kommentare","text":"Kommentare sind in diesem Zusammenhang vorallem zur Strukturierung/Abgrenzung des Codes empfohlen, und um die Verst\u00e4ndlichkeit zu erh\u00f6hen. Kommentare sollten nicht das Offensichtliche wiederholen (siehe Bild). Selbstverst\u00e4ndlich kann Code zum besseren eigenen Verst\u00e4ndnis kommentiert werden. Denken Sie aber daran, dass bei Code \u00c4nderungen auch die Kommentare mit gepflegt werden m\u00fcssen.","title":"1.1 Kommentare"},{"location":"03_coding_style.html#4-benennung","text":"Die folgenden Regelungen sind empfohlen und in keinster Weise verpflichtend.","title":"4. Benennung"},{"location":"03_coding_style.html#41-camelcase-fur-variablen-und-funktionen","text":"Variablen- und Funktionsnamen beginnen mit Kleinbuchstaben und folgen der camelCase Notation, d.h. bei zusammengesetzten Namen beginnen die Wortteile im Inneren mit einem Gro\u00dfbuchstaben. Funktionsnamen beschreiben dabei eine Aktivit\u00e4t ( z.B. calculateHorizontalPosition() ) oder eine Frage (z.B. isHit() ). Gleiches gilt f\u00fcr Attribute und Methoden.","title":"4.1 camelCase f\u00fcr Variablen und Funktionen"},{"location":"03_coding_style.html#42-unterstrich-vor-formalen-parametern","text":"Formale Parameter folgen dem Variablen-Benennungs-Schema, mit dem Zusatz eines Unterstriches am Anfang. (z.B. moveTo(_x: number, _y: number) ).","title":"4.2 Unterstrich vor formalen Parametern"},{"location":"03_coding_style.html#43-pascalcase-fur-klassen-und-interfaces","text":"Die Namen von Klassen und Interfaces beginnen mit einem Gro\u00dfbuchstaben und folgen sonst der Kamelnotation (also PascalCase). Klassen und Interfaces beschreiben im Normalfall ein bestimmtes Objekt, nicht eine Gruppe von Objekten. Dies sollte sich im Namen wiederspiegeln ( Produkt statt Produkte ).","title":"4.3 PascalCase f\u00fcr Klassen und Interfaces"},{"location":"03_coding_style.html#44-groschreibung-fur-enumeratoren","text":"Die Namen von Enumerationen und deren Elemente werden durchgehend mit Gro\u00dfbuchstaben geschreiben. Wortteile werden bei Bedarf mit Unterstrich getrennt.","title":"4.4 Gro\u00dfschreibung f\u00fcr Enumeratoren"},{"location":"03_coding_style.html#5-doppelte-und-einfache-anfuhrungszeichen","text":"Es empfielt sich, einfache Anf\u00fchrungszeichen ' ' f\u00fcr char und doppelte Anf\u00fchrungszeichen \" \" f\u00fcr Strings zu verwenden.","title":"5. Doppelte und einfache Anf\u00fchrungszeichen"},{"location":"03_coding_style.html#6-formatierung","text":"Code ist sinnvoll Formatiert mit Einsch\u00fcben etc. Im Regelfall unterst\u00fctzt VSCode dies Automatisch. Machen Sie Gebrauch von der automatischen Formatierungsfunktion. Anleitung f\u00fcr IntelliJ Anleitung f\u00fcr Visual Studio Code Anleitung f\u00fcr Eclipse","title":"6. Formatierung"},{"location":"03_coding_style.html#8-magische-zahlen","text":"Der Gebrauch von \"magischen\" Zahlen sollte vermieden werden. Solange es nicht extrem offensichtlich ist, wof\u00fcr eine Zahl steht (z.B. Math.pow(x, 5) ), sollte eine Variable (nach den oben genannten Guidelines) angelegt werden, welcher die Zahl als Wert zugewiesen wird. So entsteht der Zusammenhang zwischen der Variablen und ihrer Bedeutung, und der Wert kann an einer zentralen Stelle angepasst werden.","title":"8. \"Magische\" Zahlen"},{"location":"03_coding_style.html#9-dateinamen-und-aufteilung","text":"Dateinamen d\u00fcrfen keine Leerzeichen oder Umlaute enthalten, sind sonst aber frei w\u00e4hlbar (s.u. f\u00fcr Einschr\u00e4nkungen). Es wird empfohlen, die Zeichenwahl auf a-z, A-Z, 0-9 und _ zu beschr\u00e4nken. Code kann auf mehrere Dateien aufgeteilt werden, sofern dies sinnvoll erscheint (z.B. um eine Trennung von Funktion und Daten zu erreichen). Wenn Klassen verwendet werden, sollte jede ihre eigene Datei bekommen. Sofern eine Datei eine bestimmte Klasse enth\u00e4lt, soll die Datei mit dem Namen der Klasse benannt sein.","title":"9. Dateinamen und -aufteilung"},{"location":"03_coding_style.html#10-wiederholungen-sind-schlecht","text":"Code der sich ohne oder nur mit minimalen \u00c4nderungen wiederholt, kann in den allermeisten F\u00e4llen besser geschrieben werden, z.B. \u00fcber eine Funktion mit \u00dcbergabeparametern, oder indem man nur den ge\u00e4nderten Teil implementiert oder \u00fcberschreibt, w\u00e4hrend der Rest f\u00fcr alles gleich generiert wird. Dies hat viele Vorteile: Es macht den Code generell \u00fcbersichtlicher (und damit besser verst\u00e4ndlich), k\u00fcrzer, und wartungsfreundlicher.","title":"10. Wiederholungen sind schlecht"},{"location":"04_introduction_to_objects.html","text":"04: Einf\u00fchrung in Objekte Kurze Begriffserkl\u00e4rung Quelle: stackhowto.com Declaration Declaring a variable means the first \u201cmention\u201d of the variable, which tells the compiler \u201cHello, I am here and can be used\u201d. In a statically typed language like Java, this also means that the declared type of the variable is determined. The value itself is not determined during the declaration. String name ; int nbr ; Initialization The term initialization usually means the first assignment of a value to a variable. String name = \"Thomas\" ; int nbr = 5 ; Instantiation The term instantiation actually has nothing to do with assigning a value to a variable, even if a new object is sometimes instantiated when a variable is initialized. The term simply means the creation of a new object, i.e. an instance, from a class. String name = new String ( \"Thomas\" ); #1 Einfache Objekte und Veerbung Lernziele: * eine Klasse erzeugen * eine Klasse aufrufen * einfache Veerbung * Polymorphie (\u00dcberschreiben von Methoden) * die Verwendung von this * die Verwendung von super // main.java public class Main { public static void main ( String [] args ) { Animal myAnimal = new Animal (); myAnimal . makeSound (); Dog myDog = new Dog (); myDog . makeSound (); Cat myCat = new Cat (); myCat . makeSound (); myCat . compareToAnimal (); } } // Animal.java public class Animal { public boolean isPet ; public Animal () { System . out . println ( \"## in constructor of Animal\" ); this . isPet = false ; // it doesn't exist for our cats or dogs } public void makeSound () { System . out . println ( \"Yes, animal usually make sounds\" ); } } // Cat.java public class Cat extends Animal { public Cat () { System . out . println ( \"## in constructor of Cat\" ); this . isPet = true ; } @Override public void makeSound () { System . out . println ( \"meow meow\" ); } public void compareToAnimal () { System . out . println ( \"--- Animal ---\" ); super . makeSound (); System . out . println ( \"is alive: \" + super . isPet ); System . out . println ( \"--- Cat ---\" ); this . makeSound (); System . out . println ( \"is alive: \" + this . isPet ); } } // Dog.java public class Dog extends Animal { public Dog () { System . out . println ( \"## in constructor of Dog\" ); this . isPet = true ; } @Override public void makeSound () { System . out . println ( \"woof woof\" ); this . isPet = true ; } public void compareToAnimal () { System . out . println ( \"--- Animal ---\" ); super . makeSound (); System . out . println ( \"is alive: \" + super . isPet ); System . out . println ( \"--- Cat ---\" ); this . makeSound (); System . out . println ( \"is alive: \" + this . isPet ); } } #2 komplexere Vererbung von Klassen Lernziele: * Erweiterte Veerbung * Modifikatoren f\u00fcr Attribute * Getter und Setter * Konstruktorverkettung // main.java public class Main { public static void main ( String [] args ) { Vehicle myVehicle = new Vehicle (); System . out . println ( \"-- myVehicle:\" ); System . out . println ( \"number of wheels: \" + myVehicle . getNumberOfWheels ()); System . out . println ( \"max Speed: \" + myVehicle . getMaxSpeed ()); myVehicle . setMaxSpeed ( 150 ); System . out . println ( \"max Speed: \" + myVehicle . getMaxSpeed ()); Car myCar = new Car ( \"blue\" ); System . out . println ( \"-- myCar:\" ); System . out . println ( \"number of wheels: \" + myCar . getNumberOfWheels ()); System . out . println ( \"max Speed: \" + myCar . getMaxSpeed ()); myVehicle . setMaxSpeed ( 150 ); System . out . println ( \"max Speed: \" + myCar . getMaxSpeed ()); } } public class Vehicle { protected int numberOfWheels ; protected int maxSpeed ; public Vehicle () { System . out . println ( \"## in default constructor of Vehicle\" ); this . numberOfWheels = 4 ; this . maxSpeed = 100 ; } public Vehicle ( int numberOfWheels , int maxSpeed ) { System . out . println ( \"## in constructor of Vehicle\" ); this . numberOfWheels = numberOfWheels ; this . maxSpeed = maxSpeed ; } public int getNumberOfWheels () { return this . numberOfWheels ; } public int getMaxSpeed () { return this . maxSpeed ; } public String printMaxSpeed () { return this . maxSpeed + \" km/h\" ; } public void setMaxSpeed ( int newMaxSpeed ) { if ( newMaxSpeed < 0 ) { return ; } this . maxSpeed = newMaxSpeed ; } } public class Car extends Vehicle { private String color ; public Car ( String color ) { super ( 4 , 200 ); // always needs to be the first statement System . out . println ( \"## in constructor of Car\" ); this . color = color ; } @Override public void setMaxSpeed ( int newMaxSpeed ) { if ( newMaxSpeed < 1000 ) { System . out . println ( \"No car shall be this slow tbh\" ); return ; } this . maxSpeed = newMaxSpeed ; } } public class Car extends Vehicle { private String color ; public Car ( String color ) { super ( 4 , 200 ); // always needs to be the first statement System . out . println ( \"## in constructor of Car\" ); this . color = color ; } @Override public void setMaxSpeed ( int newMaxSpeed ) { if ( newMaxSpeed < 1000 ) { System . out . println ( \"No car shall be this slow tbh\" ); return ; } this . maxSpeed = newMaxSpeed ; } } public class Truck extends Vehicle { private boolean isFireTruck ; private final String hornSound ; public Truck ( boolean isFireTruck ) { super ( 4 , 200 ); // always needs to be the first statement System . out . println ( \"## in constructor of Truck\" ); this . isFireTruck = isFireTruck ; this . hornSound = \"test\" ; } public boolean getIsFireTruck () { return this . isFireTruck ; } } #3 static in einer Klasse Lernziele: * statische und dynamische Variablen * statische und dynamische Methoden // main.java public class Main { public static void main ( String [] args ) { Counter . printCounterStatic ( \"Static\" ); Counter . increaseCounterStatic (); Counter . printCounterStatic ( \"Static\" ); Counter myCounter = new Counter (); Counter . increaseCounterStatic (); myCounter . increaseCounterDynamic (); myCounter . printCounterDynamic ( \"Dynamic\" ); } } public class Counter { static int counterValueStatic = 0 ; int counterValueDynamic = 0 ; public static void increaseCounterStatic () { counterValueStatic ++ ; } public void increaseCounterDynamic () { this . counterValueDynamic ++ ; } public void printCounterDynamic ( String classID ) { System . out . println ( \">> execute printCounterDynamic of class \" + classID ); System . out . println ( \"static: \" + counterValueStatic ); System . out . println ( \"dynamic: \" + this . counterValueDynamic ); } public static void printCounterStatic ( String classID ) { System . out . println ( \">> execute printCounterStatic of class \" + classID ); System . out . println ( \"dynamic: \" + counterValueStatic ); } }","title":"04: Einf\u00fchrung in Objekte"},{"location":"04_introduction_to_objects.html#04-einfuhrung-in-objekte","text":"","title":"04: Einf\u00fchrung in Objekte"},{"location":"04_introduction_to_objects.html#kurze-begriffserklarung","text":"Quelle: stackhowto.com","title":"Kurze Begriffserkl\u00e4rung"},{"location":"04_introduction_to_objects.html#declaration","text":"Declaring a variable means the first \u201cmention\u201d of the variable, which tells the compiler \u201cHello, I am here and can be used\u201d. In a statically typed language like Java, this also means that the declared type of the variable is determined. The value itself is not determined during the declaration. String name ; int nbr ;","title":"Declaration"},{"location":"04_introduction_to_objects.html#initialization","text":"The term initialization usually means the first assignment of a value to a variable. String name = \"Thomas\" ; int nbr = 5 ;","title":"Initialization"},{"location":"04_introduction_to_objects.html#instantiation","text":"The term instantiation actually has nothing to do with assigning a value to a variable, even if a new object is sometimes instantiated when a variable is initialized. The term simply means the creation of a new object, i.e. an instance, from a class. String name = new String ( \"Thomas\" );","title":"Instantiation"},{"location":"04_introduction_to_objects.html#1-einfache-objekte-und-veerbung","text":"Lernziele: * eine Klasse erzeugen * eine Klasse aufrufen * einfache Veerbung * Polymorphie (\u00dcberschreiben von Methoden) * die Verwendung von this * die Verwendung von super // main.java public class Main { public static void main ( String [] args ) { Animal myAnimal = new Animal (); myAnimal . makeSound (); Dog myDog = new Dog (); myDog . makeSound (); Cat myCat = new Cat (); myCat . makeSound (); myCat . compareToAnimal (); } } // Animal.java public class Animal { public boolean isPet ; public Animal () { System . out . println ( \"## in constructor of Animal\" ); this . isPet = false ; // it doesn't exist for our cats or dogs } public void makeSound () { System . out . println ( \"Yes, animal usually make sounds\" ); } } // Cat.java public class Cat extends Animal { public Cat () { System . out . println ( \"## in constructor of Cat\" ); this . isPet = true ; } @Override public void makeSound () { System . out . println ( \"meow meow\" ); } public void compareToAnimal () { System . out . println ( \"--- Animal ---\" ); super . makeSound (); System . out . println ( \"is alive: \" + super . isPet ); System . out . println ( \"--- Cat ---\" ); this . makeSound (); System . out . println ( \"is alive: \" + this . isPet ); } } // Dog.java public class Dog extends Animal { public Dog () { System . out . println ( \"## in constructor of Dog\" ); this . isPet = true ; } @Override public void makeSound () { System . out . println ( \"woof woof\" ); this . isPet = true ; } public void compareToAnimal () { System . out . println ( \"--- Animal ---\" ); super . makeSound (); System . out . println ( \"is alive: \" + super . isPet ); System . out . println ( \"--- Cat ---\" ); this . makeSound (); System . out . println ( \"is alive: \" + this . isPet ); } }","title":"#1 Einfache Objekte und Veerbung"},{"location":"04_introduction_to_objects.html#2-komplexere-vererbung-von-klassen","text":"Lernziele: * Erweiterte Veerbung * Modifikatoren f\u00fcr Attribute * Getter und Setter * Konstruktorverkettung // main.java public class Main { public static void main ( String [] args ) { Vehicle myVehicle = new Vehicle (); System . out . println ( \"-- myVehicle:\" ); System . out . println ( \"number of wheels: \" + myVehicle . getNumberOfWheels ()); System . out . println ( \"max Speed: \" + myVehicle . getMaxSpeed ()); myVehicle . setMaxSpeed ( 150 ); System . out . println ( \"max Speed: \" + myVehicle . getMaxSpeed ()); Car myCar = new Car ( \"blue\" ); System . out . println ( \"-- myCar:\" ); System . out . println ( \"number of wheels: \" + myCar . getNumberOfWheels ()); System . out . println ( \"max Speed: \" + myCar . getMaxSpeed ()); myVehicle . setMaxSpeed ( 150 ); System . out . println ( \"max Speed: \" + myCar . getMaxSpeed ()); } } public class Vehicle { protected int numberOfWheels ; protected int maxSpeed ; public Vehicle () { System . out . println ( \"## in default constructor of Vehicle\" ); this . numberOfWheels = 4 ; this . maxSpeed = 100 ; } public Vehicle ( int numberOfWheels , int maxSpeed ) { System . out . println ( \"## in constructor of Vehicle\" ); this . numberOfWheels = numberOfWheels ; this . maxSpeed = maxSpeed ; } public int getNumberOfWheels () { return this . numberOfWheels ; } public int getMaxSpeed () { return this . maxSpeed ; } public String printMaxSpeed () { return this . maxSpeed + \" km/h\" ; } public void setMaxSpeed ( int newMaxSpeed ) { if ( newMaxSpeed < 0 ) { return ; } this . maxSpeed = newMaxSpeed ; } } public class Car extends Vehicle { private String color ; public Car ( String color ) { super ( 4 , 200 ); // always needs to be the first statement System . out . println ( \"## in constructor of Car\" ); this . color = color ; } @Override public void setMaxSpeed ( int newMaxSpeed ) { if ( newMaxSpeed < 1000 ) { System . out . println ( \"No car shall be this slow tbh\" ); return ; } this . maxSpeed = newMaxSpeed ; } } public class Car extends Vehicle { private String color ; public Car ( String color ) { super ( 4 , 200 ); // always needs to be the first statement System . out . println ( \"## in constructor of Car\" ); this . color = color ; } @Override public void setMaxSpeed ( int newMaxSpeed ) { if ( newMaxSpeed < 1000 ) { System . out . println ( \"No car shall be this slow tbh\" ); return ; } this . maxSpeed = newMaxSpeed ; } } public class Truck extends Vehicle { private boolean isFireTruck ; private final String hornSound ; public Truck ( boolean isFireTruck ) { super ( 4 , 200 ); // always needs to be the first statement System . out . println ( \"## in constructor of Truck\" ); this . isFireTruck = isFireTruck ; this . hornSound = \"test\" ; } public boolean getIsFireTruck () { return this . isFireTruck ; } }","title":"#2 komplexere Vererbung von Klassen"},{"location":"04_introduction_to_objects.html#3-static-in-einer-klasse","text":"Lernziele: * statische und dynamische Variablen * statische und dynamische Methoden // main.java public class Main { public static void main ( String [] args ) { Counter . printCounterStatic ( \"Static\" ); Counter . increaseCounterStatic (); Counter . printCounterStatic ( \"Static\" ); Counter myCounter = new Counter (); Counter . increaseCounterStatic (); myCounter . increaseCounterDynamic (); myCounter . printCounterDynamic ( \"Dynamic\" ); } } public class Counter { static int counterValueStatic = 0 ; int counterValueDynamic = 0 ; public static void increaseCounterStatic () { counterValueStatic ++ ; } public void increaseCounterDynamic () { this . counterValueDynamic ++ ; } public void printCounterDynamic ( String classID ) { System . out . println ( \">> execute printCounterDynamic of class \" + classID ); System . out . println ( \"static: \" + counterValueStatic ); System . out . println ( \"dynamic: \" + this . counterValueDynamic ); } public static void printCounterStatic ( String classID ) { System . out . println ( \">> execute printCounterStatic of class \" + classID ); System . out . println ( \"dynamic: \" + counterValueStatic ); } }","title":"#3 static in einer Klasse"},{"location":"05_types_of_objects.html","text":"05: Typen von Objekten Enumerations // SecurityLevel.java public enum SecurityLevel { LOW , MEDIUM , HIGH ; } // Main.java public class Main { public static void main ( String [] args ) { SecurityLevel networkSecurity = SecurityLevel . MEDIUM ; // comparing enum items System . out . println ( networkSecurity == SecurityLevel . HIGH ); // false System . out . println ( networkSecurity . compareTo ( SecurityLevel . LOW )); // 1 System . out . println ( networkSecurity . compareTo ( SecurityLevel . MEDIUM )); // 0 System . out . println ( networkSecurity . compareTo ( SecurityLevel . HIGH )); // -1 // print all possible values for ( SecurityLevel value : SecurityLevel . values ()) { System . out . println ( value . ordinal () + \" \" + value . name () + \" \" + value ); } switch ( networkSecurity ) { case LOW : System . out . println ( \"The network security MUST be increased!\" ); break ; case MEDIUM : System . out . println ( \"The network security needs improvements\" ); break ; case HIGH : System . out . println ( \"The network security is good so far\" ); break ; } } } Generics // Main.java public class Main /*extends Language implements Regex*/ { public static void main ( String [] args ) { SaveState < String > stateFirst = new SaveState < String > ( \"Begin of the story\" ); SaveState < String > stateSecond = new SaveState < String > ( \"Near last boss fight\" ); System . out . println ( stateFirst ); System . out . println ( stateSecond ); System . out . println ( \"second state bigger? \" + stateSecond . compareTo ( stateFirst )); System . out . println ( \"first state bigger? \" + stateFirst . compareTo ( stateSecond )); stateFirst . setSaveState ( \"Finished tutorial\" ); System . out . println ( stateFirst . getSaveState ()); } } Abstract and Interface // Regex.java public interface Regex { public String concatStrings ( String left , String right ); } // Main.java abstract class Language { public void showLanguage () { System . out . println ( \"This text is presented to you by Java\" ); } public abstract void sayHelloWorld (); } // Main.java public class Main extends Language implements Regex { public static void main ( String [] args ) { // Language myLanguage = new Language(); // 'Language' is abstract; cannot be instantiated Main myObject = new Main (); myObject . sayHelloWorld (); String wortwitz = myObject . concatStrings ( \"du\" , \"schlampe\" ); System . out . println ( wortwitz ); // duschlampe } @Override public void sayHelloWorld () { System . out . println ( \"I refuse to say that!\" ); } @Override public String concatStrings ( String left , String right ) { return left + right ; } } // SaveState.java import java.security.InvalidParameterException ; public class SaveState < T > implements Comparable < SaveState > { private T saveEntry ; private int saveID = 0 ; private static int staticSaveID ; // constructor SaveState ( T saveEntry ) throws InvalidParameterException { if ( saveEntry == null ) throw new InvalidParameterException ( \"entry shall not be null\" ); this . saveEntry = saveEntry ; this . saveID = staticSaveID ; staticSaveID ++ ; } public int getSaveID () { return this . saveID ; } public T getSaveState () { return this . saveEntry ; } public void setSaveState ( T saveEntry ) throws InvalidParameterException { if ( saveEntry == null ) throw new InvalidParameterException ( \"entry shall not be null\" ); this . saveEntry = saveEntry ; } @Override public String toString () { try { return this . saveID + \": \" + this . saveEntry . toString (); } catch ( Exception exception ) { System . out . println ( \"T.toString() for Class \" + saveEntry . getClass () + \" does not exist\" ); return null ; } } @Override public int compareTo ( SaveState object ) { if ( this . saveID > object . getSaveID ()) { return 1 ; } if ( this . saveID < object . getSaveID ()) { return - 1 ; } return 0 ; } } Collections import java.util.* ; // Main.java public class Main { public static void main ( String [] args ) { String [] alphabet = { \"bee\" , \"apple\" , \"clown\" }; System . out . println ( Arrays . toString ( alphabet ) ); ArrayList < String > myArrayList = new ArrayList < String > (); TreeSet < String > myTreeSet = new TreeSet < String > (); HashMap < Integer , String > myHashMap = new HashMap <> (); for ( String selection : alphabet ) { myArrayList . add ( selection ); myTreeSet . add ( selection ); myHashMap . put ( myHashMap . size (), selection ); } Set < Integer > mapKeys = myHashMap . keySet (); System . out . println ( mapKeys ); Collection < String > mapValues = myHashMap . values (); System . out . println ( mapValues ); Iterator < String > arrayListIterator = myArrayList . iterator (); Iterator < String > treeSetIterator = myTreeSet . iterator (); Iterator < String > hashMapIterator = myHashMap . values (). iterator (); System . out . println ( \"--- arrayList ---\" ); for ( String selectedValue : myArrayList ) { System . out . println ( selectedValue ); } System . out . println ( \"--- arrayListIterator ---\" ); while ( arrayListIterator . hasNext ()) { System . out . println ( arrayListIterator . next ()); } System . out . println ( \"--- treeSet ---\" ); for ( String selectedValue : myTreeSet ) { ystem . out . println ( selectedValue ); } System . out . println ( \"--- treeSetIterator ---\" ); while ( treeSetIterator . hasNext ()) { System . out . println ( treeSetIterator . next ()); } System . out . println ( \"--- hashMap ---\" ); for ( Map . Entry < Integer , String > pair : myHashMap . entrySet ()) { System . out . println ( pair . getKey () + \": \" + pair . getValue ()); } System . out . println ( \"--- hashMapIterator ---\" ); while ( hashMapIterator . hasNext ()) { System . out . println ( hashMapIterator . next ()); } } } List - f\u00fcr beliebig gro\u00dfe Listen, deren Elemente auch \u00fcber einen Index zugegriffen werden k\u00f6nnen, ArrayList - Indizierte Liste, deren Gr\u00f6\u00dfe dynamisch ver\u00e4ndert werden kann. Indexzugriffe sind schnell, Gr\u00f6\u00dfen\u00e4nderungen sind aufw\u00e4ndig. LinkedList - Verkettete Liste. Indexzugriffe sind langsam, Einf\u00fcgen und L\u00f6schen ist schnell. Set - zur Darstellung von Mengen HashSet - ungeordnete Datenmenge (ohne Duplikate) TreeSet - Sortierte Menge. Map - f\u00fcr Paare von Daten verschiedenen Typs. HashMap - Menge von (Schl\u00fcssel,Wert)-Paaren TreeMap - nach Schl\u00fcsseln sortierte Menge von (Schl\u00fcssel,Wert)-Paaren Collection Interface (List, Set, Map) Methode Beschreibung int size() liefert die Anzahl der Eintr\u00e4ge boolean isEmpty() pr\u00fcft, ob keine Eintr\u00e4ge vorhanden sind boolean contains(Object o) pr\u00fcft, ob o eingetragen ist boolean add(Object o) pr\u00fcft, ob alle Elemente aus c enthalten sind boolean addAll(Collection c) tr\u00e4gt alle Elemente aus c ein (optional) boolean remove(Object o) entfernt o (optional) boolean removeAll(Collection c) entfernt die in c angegebenen Elemente (optional) boolean retainAll(Collection c) entfernt alle Elemente, au\u00dfer die in c angegebenen (optional) boolean equals(Object o) pr\u00fcft, ob o mit der Collection \u00fcbereinstimmt Iterator iterator() erzeugt einen Iterator void clear() entfernt alle Elemente (optional) List Interface Methode Beschreibung Object get(int i) liefert das Element an Position i (ohne es zu entfernen) int indexOf(Object o) liefert den Index des ersten Vorkommens von o oder -1 Map Interface Methode Beschreibung boolean containsKey(Object key) pr\u00fcft, ob ein Datenpaar mit Schl\u00fcssel key eingetragen ist boolean containsValue(Object value) pr\u00fcft, ob ein Datenpaar mit Wert value eingetragen ist Object get(Object key) liefert den eingetragenen Wert zum Schl\u00fcssen key Object put(Object key, Object value) tr\u00e4gt das Datenpaar(key,value) ein (optional) boolean remove(Object key) entfernt das Datenpaar mit Schl\u00fcssel key (optional) Iteratoren (List, Set) Methode Beschreibung boolean hasNext() pr\u00fcft, ob ein weiteres Element existiert Object next() liefert das n\u00e4chste Element und schaltet weiter void remove() l\u00f6scht das aktuelle Element ListIterator (List) Methode Beschreibung boolean hasPrevious() pr\u00fcft, ob ein Vorg\u00e4nger existiert Object previous() liefert das vorherige Element void add(Object o) f\u00fcgt ein neues Element o hinter dem aktuellen Element ein void set(Object o) ersetzt das aktuelle Element durch o","title":"05: Typen von Objekten"},{"location":"05_types_of_objects.html#05-typen-von-objekten","text":"","title":"05: Typen von Objekten"},{"location":"05_types_of_objects.html#enumerations","text":"// SecurityLevel.java public enum SecurityLevel { LOW , MEDIUM , HIGH ; } // Main.java public class Main { public static void main ( String [] args ) { SecurityLevel networkSecurity = SecurityLevel . MEDIUM ; // comparing enum items System . out . println ( networkSecurity == SecurityLevel . HIGH ); // false System . out . println ( networkSecurity . compareTo ( SecurityLevel . LOW )); // 1 System . out . println ( networkSecurity . compareTo ( SecurityLevel . MEDIUM )); // 0 System . out . println ( networkSecurity . compareTo ( SecurityLevel . HIGH )); // -1 // print all possible values for ( SecurityLevel value : SecurityLevel . values ()) { System . out . println ( value . ordinal () + \" \" + value . name () + \" \" + value ); } switch ( networkSecurity ) { case LOW : System . out . println ( \"The network security MUST be increased!\" ); break ; case MEDIUM : System . out . println ( \"The network security needs improvements\" ); break ; case HIGH : System . out . println ( \"The network security is good so far\" ); break ; } } }","title":"Enumerations"},{"location":"05_types_of_objects.html#generics","text":"// Main.java public class Main /*extends Language implements Regex*/ { public static void main ( String [] args ) { SaveState < String > stateFirst = new SaveState < String > ( \"Begin of the story\" ); SaveState < String > stateSecond = new SaveState < String > ( \"Near last boss fight\" ); System . out . println ( stateFirst ); System . out . println ( stateSecond ); System . out . println ( \"second state bigger? \" + stateSecond . compareTo ( stateFirst )); System . out . println ( \"first state bigger? \" + stateFirst . compareTo ( stateSecond )); stateFirst . setSaveState ( \"Finished tutorial\" ); System . out . println ( stateFirst . getSaveState ()); } }","title":"Generics"},{"location":"05_types_of_objects.html#abstract-and-interface","text":"// Regex.java public interface Regex { public String concatStrings ( String left , String right ); } // Main.java abstract class Language { public void showLanguage () { System . out . println ( \"This text is presented to you by Java\" ); } public abstract void sayHelloWorld (); } // Main.java public class Main extends Language implements Regex { public static void main ( String [] args ) { // Language myLanguage = new Language(); // 'Language' is abstract; cannot be instantiated Main myObject = new Main (); myObject . sayHelloWorld (); String wortwitz = myObject . concatStrings ( \"du\" , \"schlampe\" ); System . out . println ( wortwitz ); // duschlampe } @Override public void sayHelloWorld () { System . out . println ( \"I refuse to say that!\" ); } @Override public String concatStrings ( String left , String right ) { return left + right ; } } // SaveState.java import java.security.InvalidParameterException ; public class SaveState < T > implements Comparable < SaveState > { private T saveEntry ; private int saveID = 0 ; private static int staticSaveID ; // constructor SaveState ( T saveEntry ) throws InvalidParameterException { if ( saveEntry == null ) throw new InvalidParameterException ( \"entry shall not be null\" ); this . saveEntry = saveEntry ; this . saveID = staticSaveID ; staticSaveID ++ ; } public int getSaveID () { return this . saveID ; } public T getSaveState () { return this . saveEntry ; } public void setSaveState ( T saveEntry ) throws InvalidParameterException { if ( saveEntry == null ) throw new InvalidParameterException ( \"entry shall not be null\" ); this . saveEntry = saveEntry ; } @Override public String toString () { try { return this . saveID + \": \" + this . saveEntry . toString (); } catch ( Exception exception ) { System . out . println ( \"T.toString() for Class \" + saveEntry . getClass () + \" does not exist\" ); return null ; } } @Override public int compareTo ( SaveState object ) { if ( this . saveID > object . getSaveID ()) { return 1 ; } if ( this . saveID < object . getSaveID ()) { return - 1 ; } return 0 ; } }","title":"Abstract and Interface"},{"location":"05_types_of_objects.html#collections","text":"import java.util.* ; // Main.java public class Main { public static void main ( String [] args ) { String [] alphabet = { \"bee\" , \"apple\" , \"clown\" }; System . out . println ( Arrays . toString ( alphabet ) ); ArrayList < String > myArrayList = new ArrayList < String > (); TreeSet < String > myTreeSet = new TreeSet < String > (); HashMap < Integer , String > myHashMap = new HashMap <> (); for ( String selection : alphabet ) { myArrayList . add ( selection ); myTreeSet . add ( selection ); myHashMap . put ( myHashMap . size (), selection ); } Set < Integer > mapKeys = myHashMap . keySet (); System . out . println ( mapKeys ); Collection < String > mapValues = myHashMap . values (); System . out . println ( mapValues ); Iterator < String > arrayListIterator = myArrayList . iterator (); Iterator < String > treeSetIterator = myTreeSet . iterator (); Iterator < String > hashMapIterator = myHashMap . values (). iterator (); System . out . println ( \"--- arrayList ---\" ); for ( String selectedValue : myArrayList ) { System . out . println ( selectedValue ); } System . out . println ( \"--- arrayListIterator ---\" ); while ( arrayListIterator . hasNext ()) { System . out . println ( arrayListIterator . next ()); } System . out . println ( \"--- treeSet ---\" ); for ( String selectedValue : myTreeSet ) { ystem . out . println ( selectedValue ); } System . out . println ( \"--- treeSetIterator ---\" ); while ( treeSetIterator . hasNext ()) { System . out . println ( treeSetIterator . next ()); } System . out . println ( \"--- hashMap ---\" ); for ( Map . Entry < Integer , String > pair : myHashMap . entrySet ()) { System . out . println ( pair . getKey () + \": \" + pair . getValue ()); } System . out . println ( \"--- hashMapIterator ---\" ); while ( hashMapIterator . hasNext ()) { System . out . println ( hashMapIterator . next ()); } } } List - f\u00fcr beliebig gro\u00dfe Listen, deren Elemente auch \u00fcber einen Index zugegriffen werden k\u00f6nnen, ArrayList - Indizierte Liste, deren Gr\u00f6\u00dfe dynamisch ver\u00e4ndert werden kann. Indexzugriffe sind schnell, Gr\u00f6\u00dfen\u00e4nderungen sind aufw\u00e4ndig. LinkedList - Verkettete Liste. Indexzugriffe sind langsam, Einf\u00fcgen und L\u00f6schen ist schnell. Set - zur Darstellung von Mengen HashSet - ungeordnete Datenmenge (ohne Duplikate) TreeSet - Sortierte Menge. Map - f\u00fcr Paare von Daten verschiedenen Typs. HashMap - Menge von (Schl\u00fcssel,Wert)-Paaren TreeMap - nach Schl\u00fcsseln sortierte Menge von (Schl\u00fcssel,Wert)-Paaren","title":"Collections"},{"location":"05_types_of_objects.html#collection-interface-list-set-map","text":"Methode Beschreibung int size() liefert die Anzahl der Eintr\u00e4ge boolean isEmpty() pr\u00fcft, ob keine Eintr\u00e4ge vorhanden sind boolean contains(Object o) pr\u00fcft, ob o eingetragen ist boolean add(Object o) pr\u00fcft, ob alle Elemente aus c enthalten sind boolean addAll(Collection c) tr\u00e4gt alle Elemente aus c ein (optional) boolean remove(Object o) entfernt o (optional) boolean removeAll(Collection c) entfernt die in c angegebenen Elemente (optional) boolean retainAll(Collection c) entfernt alle Elemente, au\u00dfer die in c angegebenen (optional) boolean equals(Object o) pr\u00fcft, ob o mit der Collection \u00fcbereinstimmt Iterator iterator() erzeugt einen Iterator void clear() entfernt alle Elemente (optional)","title":"Collection Interface (List, Set, Map)"},{"location":"05_types_of_objects.html#list-interface","text":"Methode Beschreibung Object get(int i) liefert das Element an Position i (ohne es zu entfernen) int indexOf(Object o) liefert den Index des ersten Vorkommens von o oder -1","title":"List Interface"},{"location":"05_types_of_objects.html#map-interface","text":"Methode Beschreibung boolean containsKey(Object key) pr\u00fcft, ob ein Datenpaar mit Schl\u00fcssel key eingetragen ist boolean containsValue(Object value) pr\u00fcft, ob ein Datenpaar mit Wert value eingetragen ist Object get(Object key) liefert den eingetragenen Wert zum Schl\u00fcssen key Object put(Object key, Object value) tr\u00e4gt das Datenpaar(key,value) ein (optional) boolean remove(Object key) entfernt das Datenpaar mit Schl\u00fcssel key (optional)","title":"Map Interface"},{"location":"05_types_of_objects.html#iteratoren-list-set","text":"Methode Beschreibung boolean hasNext() pr\u00fcft, ob ein weiteres Element existiert Object next() liefert das n\u00e4chste Element und schaltet weiter void remove() l\u00f6scht das aktuelle Element","title":"Iteratoren (List, Set)"},{"location":"05_types_of_objects.html#listiterator-list","text":"Methode Beschreibung boolean hasPrevious() pr\u00fcft, ob ein Vorg\u00e4nger existiert Object previous() liefert das vorherige Element void add(Object o) f\u00fcgt ein neues Element o hinter dem aktuellen Element ein void set(Object o) ersetzt das aktuelle Element durch o","title":"ListIterator (List)"},{"location":"06_java_docs.html","text":"06: JavaDoc Quelle: JavaDoc Cheatsheet Output as PDF: JavaDoc from class Main /** * This is the Main class * @version 1.0.1 * @author Justin Drtvic */ // Main.java public class Main { /** * this is the main function, which is needed to execute the code * @param args params passed by the command line */ public static void main ( String [] args ) { System . out . println ( addition ( 1 , 2 ) ); } /** * addition of two integer numbers * @param left number for left side * @param right number for right side * @return sum of two numbers * @throws IllegalArgumentException for numbers smaller than 0 * @see Math * @see Mathebibel Addition * @since Java API 7 * @deprecated deprecated since 3.0.0 */ public static int addition ( int left , int right ) { if ( left < 0 || right < 0 ) { throw new IllegalArgumentException ( \"we don't like numbers smaller than 0\" ); } return left + right ; } }","title":"06: JavaDoc"},{"location":"06_java_docs.html#06-javadoc","text":"Quelle: JavaDoc Cheatsheet Output as PDF: JavaDoc from class Main /** * This is the Main class * @version 1.0.1 * @author Justin Drtvic */ // Main.java public class Main { /** * this is the main function, which is needed to execute the code * @param args params passed by the command line */ public static void main ( String [] args ) { System . out . println ( addition ( 1 , 2 ) ); } /** * addition of two integer numbers * @param left number for left side * @param right number for right side * @return sum of two numbers * @throws IllegalArgumentException for numbers smaller than 0 * @see Math * @see Mathebibel Addition * @since Java API 7 * @deprecated deprecated since 3.0.0 */ public static int addition ( int left , int right ) { if ( left < 0 || right < 0 ) { throw new IllegalArgumentException ( \"we don't like numbers smaller than 0\" ); } return left + right ; } }","title":"06: JavaDoc"}]}; var __search = { index: Promise.resolve(local_index) }
\ No newline at end of file
+const local_index = {"config":{"indexing":"full","lang":["de"],"min_search_length":3,"prebuild_index":false,"separator":"[\\s\\-]+"},"docs":[{"location":"index.html","text":"Crashkurs Java im Modul Algorithmen und Datenstrukturen public class Main { public static void main ( String [] args ) { System . out . println ( \"Die Seite ist noch leer\" ); } }","title":"Crashkurs Java im Modul Algorithmen und Datenstrukturen"},{"location":"index.html#crashkurs-java-im-modul-algorithmen-und-datenstrukturen","text":"public class Main { public static void main ( String [] args ) { System . out . println ( \"Die Seite ist noch leer\" ); } }","title":"Crashkurs Java im Modul Algorithmen und Datenstrukturen"},{"location":"01_hello_world.html","text":"01: Hello World Approach 1: Simple String Output // main.java public class main { public static void main ( String [] args ) { System . out . println ( \"Hello, World!\" ); } } >> javac main.java >> java main Hello, World! Was sagt dieser Code nun aus? * Eine Klasse \"main\" ist \u00f6ffentlich * Dem Compiler wird die statische Methode main vorlegt * Diese wird bei jedem Java Code genutzt * Wir rufen die Klasse System auf und f\u00fchren einen println -Befehl aus * Hello, World! wird in der Konsole ausgegeben Approach 2: Using Console Arguments // main.java public class main { public static void main ( String [] args ) { System . out . println ( args [ 0 ] + \" \" + args [ 1 ] ); } } >> javac main.java >> java main Hello, World! Hello, World! Was ist nun anders? * Die Main-Methode \u00fcbergibt standardm\u00e4\u00dfig Konsolenargumente als Array vom Typ String mit dem Namen args * Jedes Argument hat einen Index im Array * F\u00fcr 2 Argumente rufen wir die ersten zwei Indexes auf, beginnend bei 0","title":"01: Hello World"},{"location":"01_hello_world.html#01-hello-world","text":"","title":"01: Hello World"},{"location":"01_hello_world.html#approach-1-simple-string-output","text":"// main.java public class main { public static void main ( String [] args ) { System . out . println ( \"Hello, World!\" ); } } >> javac main.java >> java main Hello, World! Was sagt dieser Code nun aus? * Eine Klasse \"main\" ist \u00f6ffentlich * Dem Compiler wird die statische Methode main vorlegt * Diese wird bei jedem Java Code genutzt * Wir rufen die Klasse System auf und f\u00fchren einen println -Befehl aus * Hello, World! wird in der Konsole ausgegeben","title":"Approach 1: Simple String Output"},{"location":"01_hello_world.html#approach-2-using-console-arguments","text":"// main.java public class main { public static void main ( String [] args ) { System . out . println ( args [ 0 ] + \" \" + args [ 1 ] ); } } >> javac main.java >> java main Hello, World! Hello, World! Was ist nun anders? * Die Main-Methode \u00fcbergibt standardm\u00e4\u00dfig Konsolenargumente als Array vom Typ String mit dem Namen args * Jedes Argument hat einen Index im Array * F\u00fcr 2 Argumente rufen wir die ersten zwei Indexes auf, beginnend bei 0","title":"Approach 2: Using Console Arguments"},{"location":"02_basics.html","text":"02: Basics Table of Contents Nutzung der Konsole Primitive Datentypen Nicht Primitive Datentypen Operatoren Bedingungen Schleifen Exceptions Nutzung der Konsole Ausgabe System . out . println ( \"print me and create a new line\" ); System . out . println (); // prints nothing but creates new line afterwards System . out . print ( \"print me without a new line | \" ); System . out . print ( \"print me but add a new line \\n\" ); System . out . print ( \"yeah, this is on the new line! \\n\" ); System . out . println (); // prints nothing but creates new line afterwards // https://www.digitalocean.com/community/tutorials/java-printf-method System . out . printf ( \"%s %s \\n\" , \"parameter 1\" , \"parameter 2\" ); System . out . printf ( \"%s %e %f\" , \"10.50\" , 10.50 , 10.50 ); Eingabe import java.util.Scanner ; // class and method : start Scanner myScanner = new Scanner ( System . in ); System . out . print ( \"Enter Username: \" ); String username = myScanner . nextLine (); System . out . print ( \"Enter Password: \" ); String password = myScanner . nextLine (); System . out . println ( \"your Username: \" + username + \"\\nyour password: \" + password ); // class and method : end Primitive Datentypen Quelle: w3schools.com Data Type Size Description byte 1 byte Stores whole numbers from -128 to 127 short 2 bytes Stores whole numbers from -32,768 to 32,767 int 4 bytes Stores whole numbers from -2,147,483,648 to 2,147,483,647 long 8 bytes Stores whole numbers from -9,223,372,036,854,775,808 to 9,223,372,036,854,775,807 float 4 bytes Stores fractional numbers. Sufficient for storing 6 to 7 decimal digits double 8 bytes Stores fractional numbers. Sufficient for storing 15 decimal digits boolean 1 bit Stores true or false values char 2 bytes Stores a single character/letter or ASCII values Type Casting Bei Type Casting handelt es sich um das \u00fcberf\u00fchren eines primitiven Datentypen in einen anderen. Quelle: w3schools.com Widening Casting (automatically) Hier wird ein kleinerer Typ in einen gr\u00f6\u00dferen Typ konvertiert byte -> short -> char -> int -> long -> float -> double int myInt = 9 ; double myDouble = myInt ; // Automatic casting: int to double System . out . println ( myInt ); // Outputs 9 System . out . println ( myDouble ); // Outputs 9.0 Narrowing Casting (manually) Hier wird ein gr\u00f6\u00dferer Typ in einen kleineren Typ konvertiert double -> float -> long -> int -> char -> short -> byte double myDouble = 9.78d ; int myInt = ( int ) myDouble ; // Manual casting: double to int System . out . println ( myDouble ); // Outputs 9.78 System . out . println ( myInt ); // Outputs 9 Nicht Primitive Datentypen String String ist eine Wrapperklasse, welche eine Zeichenkette aus einzelnen chars zusammenbaut. In manchen Programmiersprachen (z.B. C++) ist ein String vergleichbar mit einem char-Array. String myString = \"this is a text\" ; System . out . println ( \"myString: \" + myString ); String concatString = \"hello\" + \"World\" ; System . out . println ( \"concatString: \" + concatString ); Methoden der Standardbibliothek: Methode Beschreibung myString.charAt() Returns the char value at the specified index. myString.indexOf() Returns the index within this string of the first occurrence of the specified substring. myString.substring() Returns a string that is a substring of this string. myString.equals() Compares this string to the specified object. myString.toLowerCase() Converts all of the characters in this String to lower case. myString.toUpperCase() Converts all of the characters in this String to upper case. myString.contains() Returns true if and only if this string contains the specified sequence of char values. myString.replaceAll() Replaces each substring of this string that matches the given regular expression with the given replacement. myString.compareTo() Compares two strings lexicographically. The comparison is based on the Unicode value of each character in the strings. Numeric Datatypes Im Gegensatz zu den primitiven Datentypen werden hier \"Wrapper\" verwendet, um dynamisch mit den Werten arbeiten zu k\u00f6nnen. Das erlaubt auch die Erweiterung um verschiedene Methoden in der Standardbibliothek. Integer: Integer myNumber = 10 ; Integer . parseInt (); // Parses the string argument as a signed decimal integer. Integer . parseUnsignedInt (); // Parses the string argument as an unsigned decimal integer. Integer . valueOf (); // Returns an Integer object holding the value of the specified String. Float and Double: Double myDouble = 10.0 ; myDouble . isNaN (); // Returns true if this Double value is a Not-a-Number (NaN), false otherwise. Float myFloat = ( float ) 10.0 ; myFloat . isNaN (); // Returns true if this Float value is a Not-a-Number (NaN), false otherwise Funktionen f\u00fcr alle Numerischen Datentypen (Nicht Primitiv): Methode Beschreibung myNumber.compareTo() Compares two Integer objects numerically. myNumber.toString() Returns a String object representing this Integer's value. myNumber.intValue() Returns the value of this Integer as an int. myNumber.floatValue() Returns the value of this Integer as a float after a widening primitive conversion. myNumber.doubleValue() Returns the value of this Integer as a double after a widening primitive conversion. myNumber.shortValue() Returns the value of this Integer as a short after a narrowing primitive conversion. Arrays Bei Arrays handelt es sich um Schleifen eines bestimmten Datentypen. Sie werden verwendet, um mehrere Werte in einer Variable zu speichern. String [] myStringArray = new String [ 3 ] ; myStringArray [ 0 ] = \"ROT\" ; myStringArray [ 1 ] = \"GR\u00dcN\" ; myStringArray [ 2 ] = \"BLAU\" ; int [] myIntArray = { 0 , 1 , 2 }; System . out . println ( myIntArray . length ); // 3 System . out . println ( Arrays . toString ( myIntArray )); // [0,1,2] multidimensionale Arrays: int [][] my2DArray = { { 1 , 2 }, { 3 , 4 , 5 }, { 6 , 7 , 8 , 9 }, }; System . out . println ( my2DArray . length ); System . out . println ( my2DArray [ 0 ] . length ); for ( int row = 0 ; row < my2DArray . length ; row ++ ) { System . out . print ( \"[\" ); for ( int column = 0 ; column < my2DArray [ row ] . length ; column ++ ) { if ( column == ( my2DArray [ row ] . length - 1 ) ) { System . out . print ( my2DArray [ row ][ column ] ); continue ; } System . out . print ( my2DArray [ row ][ column ] + \", \" ); } System . out . println ( \"]\" ); } Methoden: Methode Beschreibung Arrays.toString(Array a) a string representation of the object. Arrays.copyOf(Array a, int index) Copies the specified array, truncating or padding with zeros (if necessary) so the copy has the specified length. Arrays.compare(Array a, Array b) Compares two int arrays lexicographically. Arrays.equals(Array a, Array b) Returns true if the two specified arrays of ints are equal to one another. Arrays.sort(Array a) Sorts the specified array into ascending numerical order Arrays.fill(Array a, int number) Assigns the specified int value to each element of the specified array of ints. Operatoren Arithmetic Operators int calcAddition = 20 + 10 ; // = 30 int calcSubstraction = 20 - 10 ; // = 10 int calcMultiplication = 20 * 10 ; // = 200 int calcDivision = 20 / 10 ; // = 2 int calcModulus = 20 % 3 ; // = 2 int myNumber = 10 ; myNumber ++ ; // myNumber = 11 myNumber -- ; // myNumber = 10 myNumber -- ; // myNumber = 9 Comparison Operators int biggerNumber = 20 ; int biggerNumberAgain = 20 ; int smallerNumber = 10 ; // (20 == 20) => true // (20 != 20) => false // (20 > 10) => true // (20 < 10) => false // (20 >= 10) => true // (20 >= 10) => true Bedingungen wir verwenden folgende Variablen: int biggerNumber = 20 ; int biggerNumberAgain = 20 ; int smallerNumber = 10 ; if-condition (better version) if ( biggerNumber > smallerNumber ) { System . out . println ( \"the left number is bigger!\" ); } if-condition (worse version) // prefer to not write it down like this! if ( biggerNumber == biggerNumberAgain ) System . out . println ( \"We don't do this here...\" ); if-else-condition if ( biggerNumber < smallerNumber ) { System . out . println ( \"the left number is smaller!\" ); } else if ( biggerNumber < biggerNumberAgain ) { System . out . println ( \"but this time, the left number is smaller!\" ); } else { System . out . println ( \"the left number is just too big!\" ); } switch-case int luckyNumber = 69 ; switch ( luckyNumber ) { case 13 : System . out . println ( \"some people consider 13 to be a lucky number\" ); break ; // we need this to avoid default! case 7 : System . out . println ( \"slot machines value this number high\" ); break ; // we need this to avoid default! default : System . out . println ( \"seems, your number was not lucky enough...\" ); } Schleifen while-loop int whileNumber = 3 ; while ( whileNumber > 0 ) { System . out . println ( whileNumber ); whileNumber -- ; } do-while-loop System . out . println ( \"--- doWhileNumber:\" ); int doWhileNumber = 3 ; do { System . out . println ( doWhileNumber ); doWhileNumber -- ; } while ( doWhileNumber > 0 ); for-loop System . out . println ( \"--- forNumber:\" ); for ( int iterator = 0 ; iterator <= 5 ; iterator ++ ) { System . out . println ( iterator ); } Beispiel Ausf\u00fchrung int myNumber = 1 ; // count, how many times we can add 2 until we reach 16, // but we pretend, 13 doesn't exist for reasons for ( int counter = 0 ; counter <= 10 ; counter ++ ) { myNumber += 2 ; if ( myNumber == 13 ) { continue ; } System . out . println ( counter ); if ( myNumber >= 16 ) { break ; } } Hinweis Vermeidet einfache Variablennamen wie i, u, usw.m um die Lesbarkeit einfach zu halten // for ( int i = 0 ; i < 10 ; i ++ ) { for ( int u = 30 ; i > 15 ; u ++ ) { myArray [ u ][ i ] = i + u ; } } for-each-loop arrays int [] myArray = { 1 , 2 , 3 }; for ( int selectedValue : myArray ) { System . out . println ( \"myArray: \" + selectedValue ); selectedValue = 0 ; } System . out . println ( Arrays . toString ( myArray )); for ( int selection : myArray ) { System . out . println ( selection ); } lists LinkedList < String > myLinkedList = new LinkedList <> (); myLinkedList . add ( \"List_1\" ); myLinkedList . add ( \"List_2\" ); myLinkedList . add ( \"List_3\" ); for ( int selectedValue : myArray ) { System . out . println ( selectedValue ); } maps HashMap < Integer , String > myHashMap = new HashMap <> (); myHashMap . put ( 1 , \"Larry\" ); myHashMap . put ( 2 , \"Steve\" ); myHashMap . put ( 3 , \"James\" ); myHashMap . forEach (( key , value ) -> { System . out . println ( key + \" \" + value ); }); Exceptions public class Main { public static void main ( String [] args ) { // simple exception handling try { int [] myNumbers = { 1 , 2 , 3 }; System . out . println ( myNumbers [ 10 ] ); } catch ( Exception exception ) { System . out . println ( exception ); System . out . println ( \"---\" ); } // extended exception handling try { int [] myNumbers = { 1 , 2 , 3 }; printTenthIndex ( myNumbers ); } catch ( RuntimeException exception ) { System . out . println ( \"class: \" + exception . getClass ()); // class: class java.lang.RuntimeException System . out . println ( \"cause: \" + exception . getCause ()); // cause: java.lang.RuntimeException: array is not big enough System . out . println ( \"message: \" + exception . getMessage ()); // message: index was not found } finally { System . out . println ( \"finally! The 'try catch' is finished.\" ); } } public static void printTenthIndex ( int [] array ) throws RuntimeException { Exception r = new RuntimeException ( \"array is not big enough\" ); // not every exception supports causes if ( array . length < 11 ) { throw new RuntimeException ( \"index was not found\" , r ); } System . out . println ( array [ 10 ] ); } }","title":"02: Basics"},{"location":"02_basics.html#02-basics","text":"","title":"02: Basics"},{"location":"02_basics.html#table-of-contents","text":"Nutzung der Konsole Primitive Datentypen Nicht Primitive Datentypen Operatoren Bedingungen Schleifen Exceptions","title":"Table of Contents"},{"location":"02_basics.html#nutzung-der-konsole","text":"","title":"Nutzung der Konsole"},{"location":"02_basics.html#ausgabe","text":"System . out . println ( \"print me and create a new line\" ); System . out . println (); // prints nothing but creates new line afterwards System . out . print ( \"print me without a new line | \" ); System . out . print ( \"print me but add a new line \\n\" ); System . out . print ( \"yeah, this is on the new line! \\n\" ); System . out . println (); // prints nothing but creates new line afterwards // https://www.digitalocean.com/community/tutorials/java-printf-method System . out . printf ( \"%s %s \\n\" , \"parameter 1\" , \"parameter 2\" ); System . out . printf ( \"%s %e %f\" , \"10.50\" , 10.50 , 10.50 );","title":"Ausgabe"},{"location":"02_basics.html#eingabe","text":"import java.util.Scanner ; // class and method : start Scanner myScanner = new Scanner ( System . in ); System . out . print ( \"Enter Username: \" ); String username = myScanner . nextLine (); System . out . print ( \"Enter Password: \" ); String password = myScanner . nextLine (); System . out . println ( \"your Username: \" + username + \"\\nyour password: \" + password ); // class and method : end","title":"Eingabe"},{"location":"02_basics.html#primitive-datentypen","text":"Quelle: w3schools.com Data Type Size Description byte 1 byte Stores whole numbers from -128 to 127 short 2 bytes Stores whole numbers from -32,768 to 32,767 int 4 bytes Stores whole numbers from -2,147,483,648 to 2,147,483,647 long 8 bytes Stores whole numbers from -9,223,372,036,854,775,808 to 9,223,372,036,854,775,807 float 4 bytes Stores fractional numbers. Sufficient for storing 6 to 7 decimal digits double 8 bytes Stores fractional numbers. Sufficient for storing 15 decimal digits boolean 1 bit Stores true or false values char 2 bytes Stores a single character/letter or ASCII values","title":"Primitive Datentypen"},{"location":"02_basics.html#type-casting","text":"Bei Type Casting handelt es sich um das \u00fcberf\u00fchren eines primitiven Datentypen in einen anderen. Quelle: w3schools.com","title":"Type Casting"},{"location":"02_basics.html#widening-casting-automatically","text":"Hier wird ein kleinerer Typ in einen gr\u00f6\u00dferen Typ konvertiert byte -> short -> char -> int -> long -> float -> double int myInt = 9 ; double myDouble = myInt ; // Automatic casting: int to double System . out . println ( myInt ); // Outputs 9 System . out . println ( myDouble ); // Outputs 9.0","title":"Widening Casting (automatically)"},{"location":"02_basics.html#narrowing-casting-manually","text":"Hier wird ein gr\u00f6\u00dferer Typ in einen kleineren Typ konvertiert double -> float -> long -> int -> char -> short -> byte double myDouble = 9.78d ; int myInt = ( int ) myDouble ; // Manual casting: double to int System . out . println ( myDouble ); // Outputs 9.78 System . out . println ( myInt ); // Outputs 9","title":"Narrowing Casting (manually)"},{"location":"02_basics.html#nicht-primitive-datentypen","text":"","title":"Nicht Primitive Datentypen"},{"location":"02_basics.html#string","text":"String ist eine Wrapperklasse, welche eine Zeichenkette aus einzelnen chars zusammenbaut. In manchen Programmiersprachen (z.B. C++) ist ein String vergleichbar mit einem char-Array. String myString = \"this is a text\" ; System . out . println ( \"myString: \" + myString ); String concatString = \"hello\" + \"World\" ; System . out . println ( \"concatString: \" + concatString ); Methoden der Standardbibliothek: Methode Beschreibung myString.charAt() Returns the char value at the specified index. myString.indexOf() Returns the index within this string of the first occurrence of the specified substring. myString.substring() Returns a string that is a substring of this string. myString.equals() Compares this string to the specified object. myString.toLowerCase() Converts all of the characters in this String to lower case. myString.toUpperCase() Converts all of the characters in this String to upper case. myString.contains() Returns true if and only if this string contains the specified sequence of char values. myString.replaceAll() Replaces each substring of this string that matches the given regular expression with the given replacement. myString.compareTo() Compares two strings lexicographically. The comparison is based on the Unicode value of each character in the strings.","title":"String"},{"location":"02_basics.html#numeric-datatypes","text":"Im Gegensatz zu den primitiven Datentypen werden hier \"Wrapper\" verwendet, um dynamisch mit den Werten arbeiten zu k\u00f6nnen. Das erlaubt auch die Erweiterung um verschiedene Methoden in der Standardbibliothek. Integer: Integer myNumber = 10 ; Integer . parseInt (); // Parses the string argument as a signed decimal integer. Integer . parseUnsignedInt (); // Parses the string argument as an unsigned decimal integer. Integer . valueOf (); // Returns an Integer object holding the value of the specified String. Float and Double: Double myDouble = 10.0 ; myDouble . isNaN (); // Returns true if this Double value is a Not-a-Number (NaN), false otherwise. Float myFloat = ( float ) 10.0 ; myFloat . isNaN (); // Returns true if this Float value is a Not-a-Number (NaN), false otherwise Funktionen f\u00fcr alle Numerischen Datentypen (Nicht Primitiv): Methode Beschreibung myNumber.compareTo() Compares two Integer objects numerically. myNumber.toString() Returns a String object representing this Integer's value. myNumber.intValue() Returns the value of this Integer as an int. myNumber.floatValue() Returns the value of this Integer as a float after a widening primitive conversion. myNumber.doubleValue() Returns the value of this Integer as a double after a widening primitive conversion. myNumber.shortValue() Returns the value of this Integer as a short after a narrowing primitive conversion.","title":"Numeric Datatypes"},{"location":"02_basics.html#arrays","text":"Bei Arrays handelt es sich um Schleifen eines bestimmten Datentypen. Sie werden verwendet, um mehrere Werte in einer Variable zu speichern. String [] myStringArray = new String [ 3 ] ; myStringArray [ 0 ] = \"ROT\" ; myStringArray [ 1 ] = \"GR\u00dcN\" ; myStringArray [ 2 ] = \"BLAU\" ; int [] myIntArray = { 0 , 1 , 2 }; System . out . println ( myIntArray . length ); // 3 System . out . println ( Arrays . toString ( myIntArray )); // [0,1,2] multidimensionale Arrays: int [][] my2DArray = { { 1 , 2 }, { 3 , 4 , 5 }, { 6 , 7 , 8 , 9 }, }; System . out . println ( my2DArray . length ); System . out . println ( my2DArray [ 0 ] . length ); for ( int row = 0 ; row < my2DArray . length ; row ++ ) { System . out . print ( \"[\" ); for ( int column = 0 ; column < my2DArray [ row ] . length ; column ++ ) { if ( column == ( my2DArray [ row ] . length - 1 ) ) { System . out . print ( my2DArray [ row ][ column ] ); continue ; } System . out . print ( my2DArray [ row ][ column ] + \", \" ); } System . out . println ( \"]\" ); } Methoden: Methode Beschreibung Arrays.toString(Array a) a string representation of the object. Arrays.copyOf(Array a, int index) Copies the specified array, truncating or padding with zeros (if necessary) so the copy has the specified length. Arrays.compare(Array a, Array b) Compares two int arrays lexicographically. Arrays.equals(Array a, Array b) Returns true if the two specified arrays of ints are equal to one another. Arrays.sort(Array a) Sorts the specified array into ascending numerical order Arrays.fill(Array a, int number) Assigns the specified int value to each element of the specified array of ints.","title":"Arrays"},{"location":"02_basics.html#operatoren","text":"","title":"Operatoren"},{"location":"02_basics.html#arithmetic-operators","text":"int calcAddition = 20 + 10 ; // = 30 int calcSubstraction = 20 - 10 ; // = 10 int calcMultiplication = 20 * 10 ; // = 200 int calcDivision = 20 / 10 ; // = 2 int calcModulus = 20 % 3 ; // = 2 int myNumber = 10 ; myNumber ++ ; // myNumber = 11 myNumber -- ; // myNumber = 10 myNumber -- ; // myNumber = 9","title":"Arithmetic Operators"},{"location":"02_basics.html#comparison-operators","text":"int biggerNumber = 20 ; int biggerNumberAgain = 20 ; int smallerNumber = 10 ; // (20 == 20) => true // (20 != 20) => false // (20 > 10) => true // (20 < 10) => false // (20 >= 10) => true // (20 >= 10) => true","title":"Comparison Operators"},{"location":"02_basics.html#bedingungen","text":"wir verwenden folgende Variablen: int biggerNumber = 20 ; int biggerNumberAgain = 20 ; int smallerNumber = 10 ;","title":"Bedingungen"},{"location":"02_basics.html#if-condition-better-version","text":"if ( biggerNumber > smallerNumber ) { System . out . println ( \"the left number is bigger!\" ); }","title":"if-condition (better version)"},{"location":"02_basics.html#if-condition-worse-version","text":"// prefer to not write it down like this! if ( biggerNumber == biggerNumberAgain ) System . out . println ( \"We don't do this here...\" );","title":"if-condition (worse version)"},{"location":"02_basics.html#if-else-condition","text":"if ( biggerNumber < smallerNumber ) { System . out . println ( \"the left number is smaller!\" ); } else if ( biggerNumber < biggerNumberAgain ) { System . out . println ( \"but this time, the left number is smaller!\" ); } else { System . out . println ( \"the left number is just too big!\" ); }","title":"if-else-condition"},{"location":"02_basics.html#switch-case","text":"int luckyNumber = 69 ; switch ( luckyNumber ) { case 13 : System . out . println ( \"some people consider 13 to be a lucky number\" ); break ; // we need this to avoid default! case 7 : System . out . println ( \"slot machines value this number high\" ); break ; // we need this to avoid default! default : System . out . println ( \"seems, your number was not lucky enough...\" ); }","title":"switch-case"},{"location":"02_basics.html#schleifen","text":"","title":"Schleifen"},{"location":"02_basics.html#while-loop","text":"int whileNumber = 3 ; while ( whileNumber > 0 ) { System . out . println ( whileNumber ); whileNumber -- ; }","title":"while-loop"},{"location":"02_basics.html#do-while-loop","text":"System . out . println ( \"--- doWhileNumber:\" ); int doWhileNumber = 3 ; do { System . out . println ( doWhileNumber ); doWhileNumber -- ; } while ( doWhileNumber > 0 );","title":"do-while-loop"},{"location":"02_basics.html#for-loop","text":"System . out . println ( \"--- forNumber:\" ); for ( int iterator = 0 ; iterator <= 5 ; iterator ++ ) { System . out . println ( iterator ); }","title":"for-loop"},{"location":"02_basics.html#beispiel-ausfuhrung","text":"int myNumber = 1 ; // count, how many times we can add 2 until we reach 16, // but we pretend, 13 doesn't exist for reasons for ( int counter = 0 ; counter <= 10 ; counter ++ ) { myNumber += 2 ; if ( myNumber == 13 ) { continue ; } System . out . println ( counter ); if ( myNumber >= 16 ) { break ; } }","title":"Beispiel Ausf\u00fchrung"},{"location":"02_basics.html#hinweis","text":"Vermeidet einfache Variablennamen wie i, u, usw.m um die Lesbarkeit einfach zu halten // for ( int i = 0 ; i < 10 ; i ++ ) { for ( int u = 30 ; i > 15 ; u ++ ) { myArray [ u ][ i ] = i + u ; } }","title":"Hinweis"},{"location":"02_basics.html#for-each-loop","text":"","title":"for-each-loop"},{"location":"02_basics.html#arrays_1","text":"int [] myArray = { 1 , 2 , 3 }; for ( int selectedValue : myArray ) { System . out . println ( \"myArray: \" + selectedValue ); selectedValue = 0 ; } System . out . println ( Arrays . toString ( myArray )); for ( int selection : myArray ) { System . out . println ( selection ); }","title":"arrays"},{"location":"02_basics.html#lists","text":"LinkedList < String > myLinkedList = new LinkedList <> (); myLinkedList . add ( \"List_1\" ); myLinkedList . add ( \"List_2\" ); myLinkedList . add ( \"List_3\" ); for ( int selectedValue : myArray ) { System . out . println ( selectedValue ); }","title":"lists"},{"location":"02_basics.html#maps","text":"HashMap < Integer , String > myHashMap = new HashMap <> (); myHashMap . put ( 1 , \"Larry\" ); myHashMap . put ( 2 , \"Steve\" ); myHashMap . put ( 3 , \"James\" ); myHashMap . forEach (( key , value ) -> { System . out . println ( key + \" \" + value ); });","title":"maps"},{"location":"02_basics.html#exceptions","text":"public class Main { public static void main ( String [] args ) { // simple exception handling try { int [] myNumbers = { 1 , 2 , 3 }; System . out . println ( myNumbers [ 10 ] ); } catch ( Exception exception ) { System . out . println ( exception ); System . out . println ( \"---\" ); } // extended exception handling try { int [] myNumbers = { 1 , 2 , 3 }; printTenthIndex ( myNumbers ); } catch ( RuntimeException exception ) { System . out . println ( \"class: \" + exception . getClass ()); // class: class java.lang.RuntimeException System . out . println ( \"cause: \" + exception . getCause ()); // cause: java.lang.RuntimeException: array is not big enough System . out . println ( \"message: \" + exception . getMessage ()); // message: index was not found } finally { System . out . println ( \"finally! The 'try catch' is finished.\" ); } } public static void printTenthIndex ( int [] array ) throws RuntimeException { Exception r = new RuntimeException ( \"array is not big enough\" ); // not every exception supports causes if ( array . length < 11 ) { throw new RuntimeException ( \"index was not found\" , r ); } System . out . println ( array [ 10 ] ); } }","title":"Exceptions"},{"location":"03_coding_style.html","text":"03: Coding Style Programme k\u00f6nnen sehr schnell sehr komplex werden. Daher ist es wichtig, sich an Stil-Regeln zu halten, um sie m\u00f6glichst verst\u00e4ndlich zu schreiben. 1. Selbsterkl\u00e4rend Code sollte sich so gut wie m\u00f6glich selbst erkl\u00e4ren. Dazu sind sprechende Variablen-, Funktions-, Klassennamen etc. erforderlich. Kurze Namen sind nur in kleinen G\u00fcltigkeitsbereichen oder bei klarer Bedeutung (z.B. i f\u00fcr for-Schleifen Iteratoren, y f\u00fcr vertikale Position) erlaubt. 1.1 Kommentare Kommentare sind in diesem Zusammenhang vorallem zur Strukturierung/Abgrenzung des Codes empfohlen, und um die Verst\u00e4ndlichkeit zu erh\u00f6hen. Kommentare sollten nicht das Offensichtliche wiederholen (siehe Bild). Selbstverst\u00e4ndlich kann Code zum besseren eigenen Verst\u00e4ndnis kommentiert werden. Denken Sie aber daran, dass bei Code \u00c4nderungen auch die Kommentare mit gepflegt werden m\u00fcssen. 4. Benennung Die folgenden Regelungen sind empfohlen und in keinster Weise verpflichtend. 4.1 camelCase f\u00fcr Variablen und Funktionen Variablen- und Funktionsnamen beginnen mit Kleinbuchstaben und folgen der camelCase Notation, d.h. bei zusammengesetzten Namen beginnen die Wortteile im Inneren mit einem Gro\u00dfbuchstaben. Funktionsnamen beschreiben dabei eine Aktivit\u00e4t ( z.B. calculateHorizontalPosition() ) oder eine Frage (z.B. isHit() ). Gleiches gilt f\u00fcr Attribute und Methoden. 4.2 Unterstrich vor formalen Parametern Formale Parameter folgen dem Variablen-Benennungs-Schema, mit dem Zusatz eines Unterstriches am Anfang. (z.B. moveTo(_x: number, _y: number) ). 4.3 PascalCase f\u00fcr Klassen und Interfaces Die Namen von Klassen und Interfaces beginnen mit einem Gro\u00dfbuchstaben und folgen sonst der Kamelnotation (also PascalCase). Klassen und Interfaces beschreiben im Normalfall ein bestimmtes Objekt, nicht eine Gruppe von Objekten. Dies sollte sich im Namen wiederspiegeln ( Produkt statt Produkte ). 4.4 Gro\u00dfschreibung f\u00fcr Enumeratoren Die Namen von Enumerationen und deren Elemente werden durchgehend mit Gro\u00dfbuchstaben geschreiben. Wortteile werden bei Bedarf mit Unterstrich getrennt. 5. Doppelte und einfache Anf\u00fchrungszeichen Es empfielt sich, einfache Anf\u00fchrungszeichen ' ' f\u00fcr char und doppelte Anf\u00fchrungszeichen \" \" f\u00fcr Strings zu verwenden. 6. Formatierung Code ist sinnvoll Formatiert mit Einsch\u00fcben etc. Im Regelfall unterst\u00fctzt VSCode dies Automatisch. Machen Sie Gebrauch von der automatischen Formatierungsfunktion. Anleitung f\u00fcr IntelliJ Anleitung f\u00fcr Visual Studio Code Anleitung f\u00fcr Eclipse 8. \"Magische\" Zahlen Der Gebrauch von \"magischen\" Zahlen sollte vermieden werden. Solange es nicht extrem offensichtlich ist, wof\u00fcr eine Zahl steht (z.B. Math.pow(x, 5) ), sollte eine Variable (nach den oben genannten Guidelines) angelegt werden, welcher die Zahl als Wert zugewiesen wird. So entsteht der Zusammenhang zwischen der Variablen und ihrer Bedeutung, und der Wert kann an einer zentralen Stelle angepasst werden. 9. Dateinamen und -aufteilung Dateinamen d\u00fcrfen keine Leerzeichen oder Umlaute enthalten, sind sonst aber frei w\u00e4hlbar (s.u. f\u00fcr Einschr\u00e4nkungen). Es wird empfohlen, die Zeichenwahl auf a-z, A-Z, 0-9 und _ zu beschr\u00e4nken. Code kann auf mehrere Dateien aufgeteilt werden, sofern dies sinnvoll erscheint (z.B. um eine Trennung von Funktion und Daten zu erreichen). Wenn Klassen verwendet werden, sollte jede ihre eigene Datei bekommen. Sofern eine Datei eine bestimmte Klasse enth\u00e4lt, soll die Datei mit dem Namen der Klasse benannt sein. 10. Wiederholungen sind schlecht Code der sich ohne oder nur mit minimalen \u00c4nderungen wiederholt, kann in den allermeisten F\u00e4llen besser geschrieben werden, z.B. \u00fcber eine Funktion mit \u00dcbergabeparametern, oder indem man nur den ge\u00e4nderten Teil implementiert oder \u00fcberschreibt, w\u00e4hrend der Rest f\u00fcr alles gleich generiert wird. Dies hat viele Vorteile: Es macht den Code generell \u00fcbersichtlicher (und damit besser verst\u00e4ndlich), k\u00fcrzer, und wartungsfreundlicher.","title":"03: Coding Style"},{"location":"03_coding_style.html#03-coding-style","text":"Programme k\u00f6nnen sehr schnell sehr komplex werden. Daher ist es wichtig, sich an Stil-Regeln zu halten, um sie m\u00f6glichst verst\u00e4ndlich zu schreiben.","title":"03: Coding Style"},{"location":"03_coding_style.html#1-selbsterklarend","text":"Code sollte sich so gut wie m\u00f6glich selbst erkl\u00e4ren. Dazu sind sprechende Variablen-, Funktions-, Klassennamen etc. erforderlich. Kurze Namen sind nur in kleinen G\u00fcltigkeitsbereichen oder bei klarer Bedeutung (z.B. i f\u00fcr for-Schleifen Iteratoren, y f\u00fcr vertikale Position) erlaubt.","title":"1. Selbsterkl\u00e4rend"},{"location":"03_coding_style.html#11-kommentare","text":"Kommentare sind in diesem Zusammenhang vorallem zur Strukturierung/Abgrenzung des Codes empfohlen, und um die Verst\u00e4ndlichkeit zu erh\u00f6hen. Kommentare sollten nicht das Offensichtliche wiederholen (siehe Bild). Selbstverst\u00e4ndlich kann Code zum besseren eigenen Verst\u00e4ndnis kommentiert werden. Denken Sie aber daran, dass bei Code \u00c4nderungen auch die Kommentare mit gepflegt werden m\u00fcssen.","title":"1.1 Kommentare"},{"location":"03_coding_style.html#4-benennung","text":"Die folgenden Regelungen sind empfohlen und in keinster Weise verpflichtend.","title":"4. Benennung"},{"location":"03_coding_style.html#41-camelcase-fur-variablen-und-funktionen","text":"Variablen- und Funktionsnamen beginnen mit Kleinbuchstaben und folgen der camelCase Notation, d.h. bei zusammengesetzten Namen beginnen die Wortteile im Inneren mit einem Gro\u00dfbuchstaben. Funktionsnamen beschreiben dabei eine Aktivit\u00e4t ( z.B. calculateHorizontalPosition() ) oder eine Frage (z.B. isHit() ). Gleiches gilt f\u00fcr Attribute und Methoden.","title":"4.1 camelCase f\u00fcr Variablen und Funktionen"},{"location":"03_coding_style.html#42-unterstrich-vor-formalen-parametern","text":"Formale Parameter folgen dem Variablen-Benennungs-Schema, mit dem Zusatz eines Unterstriches am Anfang. (z.B. moveTo(_x: number, _y: number) ).","title":"4.2 Unterstrich vor formalen Parametern"},{"location":"03_coding_style.html#43-pascalcase-fur-klassen-und-interfaces","text":"Die Namen von Klassen und Interfaces beginnen mit einem Gro\u00dfbuchstaben und folgen sonst der Kamelnotation (also PascalCase). Klassen und Interfaces beschreiben im Normalfall ein bestimmtes Objekt, nicht eine Gruppe von Objekten. Dies sollte sich im Namen wiederspiegeln ( Produkt statt Produkte ).","title":"4.3 PascalCase f\u00fcr Klassen und Interfaces"},{"location":"03_coding_style.html#44-groschreibung-fur-enumeratoren","text":"Die Namen von Enumerationen und deren Elemente werden durchgehend mit Gro\u00dfbuchstaben geschreiben. Wortteile werden bei Bedarf mit Unterstrich getrennt.","title":"4.4 Gro\u00dfschreibung f\u00fcr Enumeratoren"},{"location":"03_coding_style.html#5-doppelte-und-einfache-anfuhrungszeichen","text":"Es empfielt sich, einfache Anf\u00fchrungszeichen ' ' f\u00fcr char und doppelte Anf\u00fchrungszeichen \" \" f\u00fcr Strings zu verwenden.","title":"5. Doppelte und einfache Anf\u00fchrungszeichen"},{"location":"03_coding_style.html#6-formatierung","text":"Code ist sinnvoll Formatiert mit Einsch\u00fcben etc. Im Regelfall unterst\u00fctzt VSCode dies Automatisch. Machen Sie Gebrauch von der automatischen Formatierungsfunktion. Anleitung f\u00fcr IntelliJ Anleitung f\u00fcr Visual Studio Code Anleitung f\u00fcr Eclipse","title":"6. Formatierung"},{"location":"03_coding_style.html#8-magische-zahlen","text":"Der Gebrauch von \"magischen\" Zahlen sollte vermieden werden. Solange es nicht extrem offensichtlich ist, wof\u00fcr eine Zahl steht (z.B. Math.pow(x, 5) ), sollte eine Variable (nach den oben genannten Guidelines) angelegt werden, welcher die Zahl als Wert zugewiesen wird. So entsteht der Zusammenhang zwischen der Variablen und ihrer Bedeutung, und der Wert kann an einer zentralen Stelle angepasst werden.","title":"8. \"Magische\" Zahlen"},{"location":"03_coding_style.html#9-dateinamen-und-aufteilung","text":"Dateinamen d\u00fcrfen keine Leerzeichen oder Umlaute enthalten, sind sonst aber frei w\u00e4hlbar (s.u. f\u00fcr Einschr\u00e4nkungen). Es wird empfohlen, die Zeichenwahl auf a-z, A-Z, 0-9 und _ zu beschr\u00e4nken. Code kann auf mehrere Dateien aufgeteilt werden, sofern dies sinnvoll erscheint (z.B. um eine Trennung von Funktion und Daten zu erreichen). Wenn Klassen verwendet werden, sollte jede ihre eigene Datei bekommen. Sofern eine Datei eine bestimmte Klasse enth\u00e4lt, soll die Datei mit dem Namen der Klasse benannt sein.","title":"9. Dateinamen und -aufteilung"},{"location":"03_coding_style.html#10-wiederholungen-sind-schlecht","text":"Code der sich ohne oder nur mit minimalen \u00c4nderungen wiederholt, kann in den allermeisten F\u00e4llen besser geschrieben werden, z.B. \u00fcber eine Funktion mit \u00dcbergabeparametern, oder indem man nur den ge\u00e4nderten Teil implementiert oder \u00fcberschreibt, w\u00e4hrend der Rest f\u00fcr alles gleich generiert wird. Dies hat viele Vorteile: Es macht den Code generell \u00fcbersichtlicher (und damit besser verst\u00e4ndlich), k\u00fcrzer, und wartungsfreundlicher.","title":"10. Wiederholungen sind schlecht"},{"location":"04_introduction_to_objects.html","text":"04: Einf\u00fchrung in Objekte Kurze Begriffserkl\u00e4rung Quelle: stackhowto.com Declaration Declaring a variable means the first \u201cmention\u201d of the variable, which tells the compiler \u201cHello, I am here and can be used\u201d. In a statically typed language like Java, this also means that the declared type of the variable is determined. The value itself is not determined during the declaration. String name ; int nbr ; Initialization The term initialization usually means the first assignment of a value to a variable. String name = \"Thomas\" ; int nbr = 5 ; Instantiation The term instantiation actually has nothing to do with assigning a value to a variable, even if a new object is sometimes instantiated when a variable is initialized. The term simply means the creation of a new object, i.e. an instance, from a class. String name = new String ( \"Thomas\" ); Modifier Quelle: w3schools.com Access-Modifier Modifier Beschreibung public The code is accessible for all classes private The code is only accessible within the declared class protected The code is accessible in the same package and subclasses. default The code is only accessible in the same package. This is used when you don't specify a modifier. Non-Access-Modifier Modifier Beschreibung final The class cannot be inherited by other classes abstract The class cannot be used to create objects (To access an abstract class, it must be inherited from another class. #1 Einfache Objekte und Veerbung Lernziele: * eine Klasse erzeugen * eine Klasse aufrufen * einfache Veerbung * Polymorphie (\u00dcberschreiben von Methoden) * die Verwendung von this * die Verwendung von super // main.java public class Main { public static void main ( String [] args ) { Animal myAnimal = new Animal (); myAnimal . makeSound (); Dog myDog = new Dog (); myDog . makeSound (); Cat myCat = new Cat (); myCat . makeSound (); myCat . compareToAnimal (); } } // Animal.java public class Animal { public boolean isPet ; public Animal () { System . out . println ( \"## in constructor of Animal\" ); this . isPet = false ; // it doesn't exist for our cats or dogs } public void makeSound () { System . out . println ( \"Yes, animal usually make sounds\" ); } } // Cat.java public class Cat extends Animal { public Cat () { System . out . println ( \"## in constructor of Cat\" ); this . isPet = true ; } @Override public void makeSound () { System . out . println ( \"meow meow\" ); } public void compareToAnimal () { System . out . println ( \"--- Animal ---\" ); super . makeSound (); System . out . println ( \"is alive: \" + super . isPet ); System . out . println ( \"--- Cat ---\" ); this . makeSound (); System . out . println ( \"is alive: \" + this . isPet ); } } // Dog.java public class Dog extends Animal { public Dog () { System . out . println ( \"## in constructor of Dog\" ); this . isPet = true ; } @Override public void makeSound () { System . out . println ( \"woof woof\" ); this . isPet = true ; } public void compareToAnimal () { System . out . println ( \"--- Animal ---\" ); super . makeSound (); System . out . println ( \"is alive: \" + super . isPet ); System . out . println ( \"--- Cat ---\" ); this . makeSound (); System . out . println ( \"is alive: \" + this . isPet ); } } #2 komplexere Vererbung von Klassen Lernziele: * Erweiterte Veerbung * Modifikatoren f\u00fcr Attribute * Getter und Setter * Konstruktorverkettung // main.java public class Main { public static void main ( String [] args ) { Vehicle myVehicle = new Vehicle (); System . out . println ( \"-- myVehicle:\" ); System . out . println ( \"number of wheels: \" + myVehicle . getNumberOfWheels ()); System . out . println ( \"max Speed: \" + myVehicle . getMaxSpeed ()); myVehicle . setMaxSpeed ( 150 ); System . out . println ( \"max Speed: \" + myVehicle . getMaxSpeed ()); Car myCar = new Car ( \"blue\" ); System . out . println ( \"-- myCar:\" ); System . out . println ( \"number of wheels: \" + myCar . getNumberOfWheels ()); System . out . println ( \"max Speed: \" + myCar . getMaxSpeed ()); myVehicle . setMaxSpeed ( 150 ); System . out . println ( \"max Speed: \" + myCar . getMaxSpeed ()); } } public class Vehicle { protected int numberOfWheels ; protected int maxSpeed ; public Vehicle () { System . out . println ( \"## in default constructor of Vehicle\" ); this . numberOfWheels = 4 ; this . maxSpeed = 100 ; } public Vehicle ( int numberOfWheels , int maxSpeed ) { System . out . println ( \"## in constructor of Vehicle\" ); this . numberOfWheels = numberOfWheels ; this . maxSpeed = maxSpeed ; } public int getNumberOfWheels () { return this . numberOfWheels ; } public int getMaxSpeed () { return this . maxSpeed ; } public String printMaxSpeed () { return this . maxSpeed + \" km/h\" ; } public void setMaxSpeed ( int newMaxSpeed ) { if ( newMaxSpeed < 0 ) { return ; } this . maxSpeed = newMaxSpeed ; } } public class Car extends Vehicle { private String color ; public Car ( String color ) { super ( 4 , 200 ); // always needs to be the first statement System . out . println ( \"## in constructor of Car\" ); this . color = color ; } @Override public void setMaxSpeed ( int newMaxSpeed ) { if ( newMaxSpeed < 1000 ) { System . out . println ( \"No car shall be this slow tbh\" ); return ; } this . maxSpeed = newMaxSpeed ; } } public class Car extends Vehicle { private String color ; public Car ( String color ) { super ( 4 , 200 ); // always needs to be the first statement System . out . println ( \"## in constructor of Car\" ); this . color = color ; } @Override public void setMaxSpeed ( int newMaxSpeed ) { if ( newMaxSpeed < 1000 ) { System . out . println ( \"No car shall be this slow tbh\" ); return ; } this . maxSpeed = newMaxSpeed ; } } public class Truck extends Vehicle { private boolean isFireTruck ; private final String hornSound ; public Truck ( boolean isFireTruck ) { super ( 4 , 200 ); // always needs to be the first statement System . out . println ( \"## in constructor of Truck\" ); this . isFireTruck = isFireTruck ; this . hornSound = \"test\" ; } public boolean getIsFireTruck () { return this . isFireTruck ; } } #3 static in einer Klasse Lernziele: * statische und dynamische Variablen * statische und dynamische Methoden // main.java public class Main { public static void main ( String [] args ) { Counter . printCounterStatic ( \"Static\" ); Counter . increaseCounterStatic (); Counter . printCounterStatic ( \"Static\" ); Counter myCounter = new Counter (); Counter . increaseCounterStatic (); myCounter . increaseCounterDynamic (); myCounter . printCounterDynamic ( \"Dynamic\" ); } } public class Counter { static int counterValueStatic = 0 ; int counterValueDynamic = 0 ; public static void increaseCounterStatic () { counterValueStatic ++ ; } public void increaseCounterDynamic () { this . counterValueDynamic ++ ; } public void printCounterDynamic ( String classID ) { System . out . println ( \">> execute printCounterDynamic of class \" + classID ); System . out . println ( \"static: \" + counterValueStatic ); System . out . println ( \"dynamic: \" + this . counterValueDynamic ); } public static void printCounterStatic ( String classID ) { System . out . println ( \">> execute printCounterStatic of class \" + classID ); System . out . println ( \"dynamic: \" + counterValueStatic ); } }","title":"04: Einf\u00fchrung in Objekte"},{"location":"04_introduction_to_objects.html#04-einfuhrung-in-objekte","text":"","title":"04: Einf\u00fchrung in Objekte"},{"location":"04_introduction_to_objects.html#kurze-begriffserklarung","text":"Quelle: stackhowto.com","title":"Kurze Begriffserkl\u00e4rung"},{"location":"04_introduction_to_objects.html#declaration","text":"Declaring a variable means the first \u201cmention\u201d of the variable, which tells the compiler \u201cHello, I am here and can be used\u201d. 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String name = new String ( \"Thomas\" );","title":"Instantiation"},{"location":"04_introduction_to_objects.html#modifier","text":"Quelle: w3schools.com","title":"Modifier"},{"location":"04_introduction_to_objects.html#access-modifier","text":"Modifier Beschreibung public The code is accessible for all classes private The code is only accessible within the declared class protected The code is accessible in the same package and subclasses. default The code is only accessible in the same package. This is used when you don't specify a modifier.","title":"Access-Modifier"},{"location":"04_introduction_to_objects.html#non-access-modifier","text":"Modifier Beschreibung final The class cannot be inherited by other classes abstract The class cannot be used to create objects (To access an abstract class, it must be inherited from another class.","title":"Non-Access-Modifier"},{"location":"04_introduction_to_objects.html#1-einfache-objekte-und-veerbung","text":"Lernziele: * eine Klasse erzeugen * eine Klasse aufrufen * einfache Veerbung * Polymorphie (\u00dcberschreiben von Methoden) * die Verwendung von this * die Verwendung von super // main.java public class Main { public static void main ( String [] args ) { Animal myAnimal = new Animal (); myAnimal . makeSound (); Dog myDog = new Dog (); myDog . makeSound (); Cat myCat = new Cat (); myCat . makeSound (); myCat . compareToAnimal (); } } // Animal.java public class Animal { public boolean isPet ; public Animal () { System . out . println ( \"## in constructor of Animal\" ); this . isPet = false ; // it doesn't exist for our cats or dogs } public void makeSound () { System . out . println ( \"Yes, animal usually make sounds\" ); } } // Cat.java public class Cat extends Animal { public Cat () { System . out . println ( \"## in constructor of Cat\" ); this . isPet = true ; } @Override public void makeSound () { System . out . println ( \"meow meow\" ); } public void compareToAnimal () { System . out . println ( \"--- Animal ---\" ); super . makeSound (); System . out . println ( \"is alive: \" + super . isPet ); System . out . println ( \"--- Cat ---\" ); this . makeSound (); System . out . println ( \"is alive: \" + this . isPet ); } } // Dog.java public class Dog extends Animal { public Dog () { System . out . println ( \"## in constructor of Dog\" ); this . isPet = true ; } @Override public void makeSound () { System . out . println ( \"woof woof\" ); this . isPet = true ; } public void compareToAnimal () { System . out . println ( \"--- Animal ---\" ); super . makeSound (); System . out . println ( \"is alive: \" + super . isPet ); System . out . println ( \"--- Cat ---\" ); this . makeSound (); System . out . println ( \"is alive: \" + this . isPet ); } }","title":"#1 Einfache Objekte und Veerbung"},{"location":"04_introduction_to_objects.html#2-komplexere-vererbung-von-klassen","text":"Lernziele: * Erweiterte Veerbung * Modifikatoren f\u00fcr Attribute * Getter und Setter * Konstruktorverkettung // main.java public class Main { public static void main ( String [] args ) { Vehicle myVehicle = new Vehicle (); System . out . println ( \"-- myVehicle:\" ); System . out . println ( \"number of wheels: \" + myVehicle . getNumberOfWheels ()); System . out . println ( \"max Speed: \" + myVehicle . getMaxSpeed ()); myVehicle . setMaxSpeed ( 150 ); System . out . println ( \"max Speed: \" + myVehicle . getMaxSpeed ()); Car myCar = new Car ( \"blue\" ); System . out . println ( \"-- myCar:\" ); System . out . println ( \"number of wheels: \" + myCar . getNumberOfWheels ()); System . out . println ( \"max Speed: \" + myCar . getMaxSpeed ()); myVehicle . setMaxSpeed ( 150 ); System . out . println ( \"max Speed: \" + myCar . getMaxSpeed ()); } } public class Vehicle { protected int numberOfWheels ; protected int maxSpeed ; public Vehicle () { System . out . println ( \"## in default constructor of Vehicle\" ); this . numberOfWheels = 4 ; this . maxSpeed = 100 ; } public Vehicle ( int numberOfWheels , int maxSpeed ) { System . out . println ( \"## in constructor of Vehicle\" ); this . numberOfWheels = numberOfWheels ; this . maxSpeed = maxSpeed ; } public int getNumberOfWheels () { return this . numberOfWheels ; } public int getMaxSpeed () { return this . maxSpeed ; } public String printMaxSpeed () { return this . maxSpeed + \" km/h\" ; } public void setMaxSpeed ( int newMaxSpeed ) { if ( newMaxSpeed < 0 ) { return ; } this . maxSpeed = newMaxSpeed ; } } public class Car extends Vehicle { private String color ; public Car ( String color ) { super ( 4 , 200 ); // always needs to be the first statement System . out . println ( \"## in constructor of Car\" ); this . color = color ; } @Override public void setMaxSpeed ( int newMaxSpeed ) { if ( newMaxSpeed < 1000 ) { System . out . println ( \"No car shall be this slow tbh\" ); return ; } this . maxSpeed = newMaxSpeed ; } } public class Car extends Vehicle { private String color ; public Car ( String color ) { super ( 4 , 200 ); // always needs to be the first statement System . out . println ( \"## in constructor of Car\" ); this . color = color ; } @Override public void setMaxSpeed ( int newMaxSpeed ) { if ( newMaxSpeed < 1000 ) { System . out . println ( \"No car shall be this slow tbh\" ); return ; } this . maxSpeed = newMaxSpeed ; } } public class Truck extends Vehicle { private boolean isFireTruck ; private final String hornSound ; public Truck ( boolean isFireTruck ) { super ( 4 , 200 ); // always needs to be the first statement System . out . println ( \"## in constructor of Truck\" ); this . isFireTruck = isFireTruck ; this . hornSound = \"test\" ; } public boolean getIsFireTruck () { return this . isFireTruck ; } }","title":"#2 komplexere Vererbung von Klassen"},{"location":"04_introduction_to_objects.html#3-static-in-einer-klasse","text":"Lernziele: * statische und dynamische Variablen * statische und dynamische Methoden // main.java public class Main { public static void main ( String [] args ) { Counter . printCounterStatic ( \"Static\" ); Counter . increaseCounterStatic (); Counter . printCounterStatic ( \"Static\" ); Counter myCounter = new Counter (); Counter . increaseCounterStatic (); myCounter . increaseCounterDynamic (); myCounter . printCounterDynamic ( \"Dynamic\" ); } } public class Counter { static int counterValueStatic = 0 ; int counterValueDynamic = 0 ; public static void increaseCounterStatic () { counterValueStatic ++ ; } public void increaseCounterDynamic () { this . counterValueDynamic ++ ; } public void printCounterDynamic ( String classID ) { System . out . println ( \">> execute printCounterDynamic of class \" + classID ); System . out . println ( \"static: \" + counterValueStatic ); System . out . println ( \"dynamic: \" + this . counterValueDynamic ); } public static void printCounterStatic ( String classID ) { System . out . println ( \">> execute printCounterStatic of class \" + classID ); System . out . println ( \"dynamic: \" + counterValueStatic ); } }","title":"#3 static in einer Klasse"},{"location":"05_types_of_objects.html","text":"05: Typen von Objekten Enumerations // SecurityLevel.java public enum SecurityLevel { LOW , MEDIUM , HIGH ; } // Main.java public class Main { public static void main ( String [] args ) { SecurityLevel networkSecurity = SecurityLevel . MEDIUM ; // comparing enum items System . out . println ( networkSecurity == SecurityLevel . HIGH ); // false System . out . println ( networkSecurity . compareTo ( SecurityLevel . LOW )); // 1 System . out . println ( networkSecurity . compareTo ( SecurityLevel . MEDIUM )); // 0 System . out . println ( networkSecurity . compareTo ( SecurityLevel . HIGH )); // -1 // print all possible values for ( SecurityLevel value : SecurityLevel . values ()) { System . out . println ( value . ordinal () + \" \" + value . name () + \" \" + value ); } switch ( networkSecurity ) { case LOW : System . out . println ( \"The network security MUST be increased!\" ); break ; case MEDIUM : System . out . println ( \"The network security needs improvements\" ); break ; case HIGH : System . out . println ( \"The network security is good so far\" ); break ; } } } Generics // Main.java public class Main /*extends Language implements Regex*/ { public static void main ( String [] args ) { SaveState < String > stateFirst = new SaveState < String > ( \"Begin of the story\" ); SaveState < String > stateSecond = new SaveState < String > ( \"Near last boss fight\" ); System . out . println ( stateFirst ); System . out . println ( stateSecond ); System . out . println ( \"second state bigger? \" + stateSecond . compareTo ( stateFirst )); System . out . println ( \"first state bigger? \" + stateFirst . compareTo ( stateSecond )); stateFirst . setSaveState ( \"Finished tutorial\" ); System . out . println ( stateFirst . getSaveState ()); } } // SaveState.java import java.security.InvalidParameterException ; public class SaveState < T > implements Comparable < SaveState > { private T saveEntry ; private int saveID = 0 ; private static int staticSaveID ; // constructor SaveState ( T saveEntry ) throws InvalidParameterException { if ( saveEntry == null ) throw new InvalidParameterException ( \"entry shall not be null\" ); this . saveEntry = saveEntry ; this . saveID = staticSaveID ; staticSaveID ++ ; } public int getSaveID () { return this . saveID ; } public T getSaveState () { return this . saveEntry ; } public void setSaveState ( T saveEntry ) throws InvalidParameterException { if ( saveEntry == null ) throw new InvalidParameterException ( \"entry shall not be null\" ); this . saveEntry = saveEntry ; } @Override public String toString () { try { return this . saveID + \": \" + this . saveEntry . toString (); } catch ( Exception exception ) { System . out . println ( \"T.toString() for Class \" + saveEntry . getClass () + \" does not exist\" ); return null ; } } @Override public int compareTo ( SaveState object ) { if ( this . saveID > object . getSaveID ()) { return 1 ; } if ( this . saveID < object . getSaveID ()) { return - 1 ; } return 0 ; } } Abstract and Interface // Regex.java public interface Regex { public String concatStrings ( String left , String right ); } // Main.java abstract class Language { public void showLanguage () { System . out . println ( \"This text is presented to you by Java\" ); } public abstract void sayHelloWorld (); } // Main.java public class Main extends Language implements Regex { public static void main ( String [] args ) { // Language myLanguage = new Language(); // 'Language' is abstract; cannot be instantiated Main myObject = new Main (); myObject . sayHelloWorld (); String wortwitz = myObject . concatStrings ( \"du\" , \"schlampe\" ); System . out . println ( wortwitz ); // duschlampe } @Override public void sayHelloWorld () { System . out . println ( \"I refuse to say that!\" ); } @Override public String concatStrings ( String left , String right ) { return left + right ; } } Collections import java.util.* ; // Main.java public class Main { public static void main ( String [] args ) { String [] alphabet = { \"bee\" , \"apple\" , \"clown\" }; System . out . println ( Arrays . toString ( alphabet ) ); ArrayList < String > myArrayList = new ArrayList < String > (); TreeSet < String > myTreeSet = new TreeSet < String > (); HashMap < Integer , String > myHashMap = new HashMap <> (); for ( String selection : alphabet ) { myArrayList . add ( selection ); myTreeSet . add ( selection ); myHashMap . put ( myHashMap . size (), selection ); } Set < Integer > mapKeys = myHashMap . keySet (); System . out . println ( mapKeys ); Collection < String > mapValues = myHashMap . values (); System . out . println ( mapValues ); Iterator < String > arrayListIterator = myArrayList . iterator (); Iterator < String > treeSetIterator = myTreeSet . iterator (); Iterator < String > hashMapIterator = myHashMap . values (). iterator (); System . out . println ( \"--- arrayList ---\" ); for ( String selectedValue : myArrayList ) { System . out . println ( selectedValue ); } System . out . println ( \"--- arrayListIterator ---\" ); while ( arrayListIterator . hasNext ()) { System . out . println ( arrayListIterator . next ()); } System . out . println ( \"--- treeSet ---\" ); for ( String selectedValue : myTreeSet ) { ystem . out . println ( selectedValue ); } System . out . println ( \"--- treeSetIterator ---\" ); while ( treeSetIterator . hasNext ()) { System . out . println ( treeSetIterator . next ()); } System . out . println ( \"--- hashMap ---\" ); for ( Map . Entry < Integer , String > pair : myHashMap . entrySet ()) { System . out . println ( pair . getKey () + \": \" + pair . getValue ()); } System . out . println ( \"--- hashMapIterator ---\" ); while ( hashMapIterator . hasNext ()) { System . out . println ( hashMapIterator . next ()); } } } List - f\u00fcr beliebig gro\u00dfe Listen, deren Elemente auch \u00fcber einen Index zugegriffen werden k\u00f6nnen, ArrayList - Indizierte Liste, deren Gr\u00f6\u00dfe dynamisch ver\u00e4ndert werden kann. Indexzugriffe sind schnell, Gr\u00f6\u00dfen\u00e4nderungen sind aufw\u00e4ndig. LinkedList - Verkettete Liste. Indexzugriffe sind langsam, Einf\u00fcgen und L\u00f6schen ist schnell. Set - zur Darstellung von Mengen HashSet - ungeordnete Datenmenge (ohne Duplikate) TreeSet - Sortierte Menge. Map - f\u00fcr Paare von Daten verschiedenen Typs. HashMap - Menge von (Schl\u00fcssel,Wert)-Paaren TreeMap - nach Schl\u00fcsseln sortierte Menge von (Schl\u00fcssel,Wert)-Paaren Collection Interface (List, Set, Map) Methode Beschreibung int size() liefert die Anzahl der Eintr\u00e4ge boolean isEmpty() pr\u00fcft, ob keine Eintr\u00e4ge vorhanden sind boolean contains(Object o) pr\u00fcft, ob o eingetragen ist boolean add(Object o) pr\u00fcft, ob alle Elemente aus c enthalten sind boolean addAll(Collection c) tr\u00e4gt alle Elemente aus c ein (optional) boolean remove(Object o) entfernt o (optional) boolean removeAll(Collection c) entfernt die in c angegebenen Elemente (optional) boolean retainAll(Collection c) entfernt alle Elemente, au\u00dfer die in c angegebenen (optional) boolean equals(Object o) pr\u00fcft, ob o mit der Collection \u00fcbereinstimmt Iterator iterator() erzeugt einen Iterator void clear() entfernt alle Elemente (optional) List Interface Methode Beschreibung Object get(int i) liefert das Element an Position i (ohne es zu entfernen) int indexOf(Object o) liefert den Index des ersten Vorkommens von o oder -1 Map Interface Methode Beschreibung boolean containsKey(Object key) pr\u00fcft, ob ein Datenpaar mit Schl\u00fcssel key eingetragen ist boolean containsValue(Object value) pr\u00fcft, ob ein Datenpaar mit Wert value eingetragen ist Object get(Object key) liefert den eingetragenen Wert zum Schl\u00fcssen key Object put(Object key, Object value) tr\u00e4gt das Datenpaar(key,value) ein (optional) boolean remove(Object key) entfernt das Datenpaar mit Schl\u00fcssel key (optional) Iteratoren (List, Set) Methode Beschreibung boolean hasNext() pr\u00fcft, ob ein weiteres Element existiert Object next() liefert das n\u00e4chste Element und schaltet weiter void remove() l\u00f6scht das aktuelle Element ListIterator (List) Methode Beschreibung boolean hasPrevious() pr\u00fcft, ob ein Vorg\u00e4nger existiert Object previous() liefert das vorherige Element void add(Object o) f\u00fcgt ein neues Element o hinter dem aktuellen Element ein void set(Object o) ersetzt das aktuelle Element durch o","title":"05: Typen von Objekten"},{"location":"05_types_of_objects.html#05-typen-von-objekten","text":"","title":"05: Typen von Objekten"},{"location":"05_types_of_objects.html#enumerations","text":"// SecurityLevel.java public enum SecurityLevel { LOW , MEDIUM , HIGH ; } // Main.java public class Main { public static void main ( String [] args ) { SecurityLevel networkSecurity = SecurityLevel . MEDIUM ; // comparing enum items System . out . println ( networkSecurity == SecurityLevel . HIGH ); // false System . out . println ( networkSecurity . compareTo ( SecurityLevel . LOW )); // 1 System . out . println ( networkSecurity . compareTo ( SecurityLevel . MEDIUM )); // 0 System . out . println ( networkSecurity . compareTo ( SecurityLevel . HIGH )); // -1 // print all possible values for ( SecurityLevel value : SecurityLevel . values ()) { System . out . println ( value . ordinal () + \" \" + value . name () + \" \" + value ); } switch ( networkSecurity ) { case LOW : System . out . println ( \"The network security MUST be increased!\" ); break ; case MEDIUM : System . out . println ( \"The network security needs improvements\" ); break ; case HIGH : System . out . println ( \"The network security is good so far\" ); break ; } } }","title":"Enumerations"},{"location":"05_types_of_objects.html#generics","text":"// Main.java public class Main /*extends Language implements Regex*/ { public static void main ( String [] args ) { SaveState < String > stateFirst = new SaveState < String > ( \"Begin of the story\" ); SaveState < String > stateSecond = new SaveState < String > ( \"Near last boss fight\" ); System . out . println ( stateFirst ); System . out . println ( stateSecond ); System . out . println ( \"second state bigger? \" + stateSecond . compareTo ( stateFirst )); System . out . println ( \"first state bigger? \" + stateFirst . compareTo ( stateSecond )); stateFirst . setSaveState ( \"Finished tutorial\" ); System . out . println ( stateFirst . getSaveState ()); } } // SaveState.java import java.security.InvalidParameterException ; public class SaveState < T > implements Comparable < SaveState > { private T saveEntry ; private int saveID = 0 ; private static int staticSaveID ; // constructor SaveState ( T saveEntry ) throws InvalidParameterException { if ( saveEntry == null ) throw new InvalidParameterException ( \"entry shall not be null\" ); this . saveEntry = saveEntry ; this . saveID = staticSaveID ; staticSaveID ++ ; } public int getSaveID () { return this . saveID ; } public T getSaveState () { return this . saveEntry ; } public void setSaveState ( T saveEntry ) throws InvalidParameterException { if ( saveEntry == null ) throw new InvalidParameterException ( \"entry shall not be null\" ); this . saveEntry = saveEntry ; } @Override public String toString () { try { return this . saveID + \": \" + this . saveEntry . toString (); } catch ( Exception exception ) { System . out . println ( \"T.toString() for Class \" + saveEntry . getClass () + \" does not exist\" ); return null ; } } @Override public int compareTo ( SaveState object ) { if ( this . saveID > object . getSaveID ()) { return 1 ; } if ( this . saveID < object . getSaveID ()) { return - 1 ; } return 0 ; } }","title":"Generics"},{"location":"05_types_of_objects.html#abstract-and-interface","text":"// Regex.java public interface Regex { public String concatStrings ( String left , String right ); } // Main.java abstract class Language { public void showLanguage () { System . out . println ( \"This text is presented to you by Java\" ); } public abstract void sayHelloWorld (); } // Main.java public class Main extends Language implements Regex { public static void main ( String [] args ) { // Language myLanguage = new Language(); // 'Language' is abstract; cannot be instantiated Main myObject = new Main (); myObject . sayHelloWorld (); String wortwitz = myObject . concatStrings ( \"du\" , \"schlampe\" ); System . out . println ( wortwitz ); // duschlampe } @Override public void sayHelloWorld () { System . out . println ( \"I refuse to say that!\" ); } @Override public String concatStrings ( String left , String right ) { return left + right ; } }","title":"Abstract and Interface"},{"location":"05_types_of_objects.html#collections","text":"import java.util.* ; // Main.java public class Main { public static void main ( String [] args ) { String [] alphabet = { \"bee\" , \"apple\" , \"clown\" }; System . out . println ( Arrays . toString ( alphabet ) ); ArrayList < String > myArrayList = new ArrayList < String > (); TreeSet < String > myTreeSet = new TreeSet < String > (); HashMap < Integer , String > myHashMap = new HashMap <> (); for ( String selection : alphabet ) { myArrayList . add ( selection ); myTreeSet . add ( selection ); myHashMap . put ( myHashMap . size (), selection ); } Set < Integer > mapKeys = myHashMap . keySet (); System . out . println ( mapKeys ); Collection < String > mapValues = myHashMap . values (); System . out . println ( mapValues ); Iterator < String > arrayListIterator = myArrayList . iterator (); Iterator < String > treeSetIterator = myTreeSet . iterator (); Iterator < String > hashMapIterator = myHashMap . values (). iterator (); System . out . println ( \"--- arrayList ---\" ); for ( String selectedValue : myArrayList ) { System . out . println ( selectedValue ); } System . out . println ( \"--- arrayListIterator ---\" ); while ( arrayListIterator . hasNext ()) { System . out . println ( arrayListIterator . next ()); } System . out . println ( \"--- treeSet ---\" ); for ( String selectedValue : myTreeSet ) { ystem . out . println ( selectedValue ); } System . out . println ( \"--- treeSetIterator ---\" ); while ( treeSetIterator . hasNext ()) { System . out . println ( treeSetIterator . next ()); } System . out . println ( \"--- hashMap ---\" ); for ( Map . Entry < Integer , String > pair : myHashMap . entrySet ()) { System . out . println ( pair . getKey () + \": \" + pair . getValue ()); } System . out . println ( \"--- hashMapIterator ---\" ); while ( hashMapIterator . hasNext ()) { System . out . println ( hashMapIterator . next ()); } } } List - f\u00fcr beliebig gro\u00dfe Listen, deren Elemente auch \u00fcber einen Index zugegriffen werden k\u00f6nnen, ArrayList - Indizierte Liste, deren Gr\u00f6\u00dfe dynamisch ver\u00e4ndert werden kann. Indexzugriffe sind schnell, Gr\u00f6\u00dfen\u00e4nderungen sind aufw\u00e4ndig. LinkedList - Verkettete Liste. Indexzugriffe sind langsam, Einf\u00fcgen und L\u00f6schen ist schnell. Set - zur Darstellung von Mengen HashSet - ungeordnete Datenmenge (ohne Duplikate) TreeSet - Sortierte Menge. Map - f\u00fcr Paare von Daten verschiedenen Typs. HashMap - Menge von (Schl\u00fcssel,Wert)-Paaren TreeMap - nach Schl\u00fcsseln sortierte Menge von (Schl\u00fcssel,Wert)-Paaren","title":"Collections"},{"location":"05_types_of_objects.html#collection-interface-list-set-map","text":"Methode Beschreibung int size() liefert die Anzahl der Eintr\u00e4ge boolean isEmpty() pr\u00fcft, ob keine Eintr\u00e4ge vorhanden sind boolean contains(Object o) pr\u00fcft, ob o eingetragen ist boolean add(Object o) pr\u00fcft, ob alle Elemente aus c enthalten sind boolean addAll(Collection c) tr\u00e4gt alle Elemente aus c ein (optional) boolean remove(Object o) entfernt o (optional) boolean removeAll(Collection c) entfernt die in c angegebenen Elemente (optional) boolean retainAll(Collection c) entfernt alle Elemente, au\u00dfer die in c angegebenen (optional) boolean equals(Object o) pr\u00fcft, ob o mit der Collection \u00fcbereinstimmt Iterator iterator() erzeugt einen Iterator void clear() entfernt alle Elemente (optional)","title":"Collection Interface (List, Set, Map)"},{"location":"05_types_of_objects.html#list-interface","text":"Methode Beschreibung Object get(int i) liefert das Element an Position i (ohne es zu entfernen) int indexOf(Object o) liefert den Index des ersten Vorkommens von o oder -1","title":"List Interface"},{"location":"05_types_of_objects.html#map-interface","text":"Methode Beschreibung boolean containsKey(Object key) pr\u00fcft, ob ein Datenpaar mit Schl\u00fcssel key eingetragen ist boolean containsValue(Object value) pr\u00fcft, ob ein Datenpaar mit Wert value eingetragen ist Object get(Object key) liefert den eingetragenen Wert zum Schl\u00fcssen key Object put(Object key, Object value) tr\u00e4gt das Datenpaar(key,value) ein (optional) boolean remove(Object key) entfernt das Datenpaar mit Schl\u00fcssel key (optional)","title":"Map Interface"},{"location":"05_types_of_objects.html#iteratoren-list-set","text":"Methode Beschreibung boolean hasNext() pr\u00fcft, ob ein weiteres Element existiert Object next() liefert das n\u00e4chste Element und schaltet weiter void remove() l\u00f6scht das aktuelle Element","title":"Iteratoren (List, Set)"},{"location":"05_types_of_objects.html#listiterator-list","text":"Methode Beschreibung boolean hasPrevious() pr\u00fcft, ob ein Vorg\u00e4nger existiert Object previous() liefert das vorherige Element void add(Object o) f\u00fcgt ein neues Element o hinter dem aktuellen Element ein void set(Object o) ersetzt das aktuelle Element durch o","title":"ListIterator (List)"},{"location":"06_java_docs.html","text":"06: JavaDoc Quelle: JavaDoc Cheatsheet Output as PDF: JavaDoc from class Main /** * This is the Main class * @version 1.0.1 * @author Justin Drtvic */ // Main.java public class Main { /** * this is the main function, which is needed to execute the code * @param args params passed by the command line */ public static void main ( String [] args ) { System . out . println ( addition ( 1 , 2 ) ); } /** * addition of two integer numbers * @param left number for left side * @param right number for right side * @return sum of two numbers * @throws IllegalArgumentException for numbers smaller than 0 * @see Math * @see Mathebibel Addition * @since Java API 7 * @deprecated deprecated since 3.0.0 */ public static int addition ( int left , int right ) { if ( left < 0 || right < 0 ) { throw new IllegalArgumentException ( \"we don't like numbers smaller than 0\" ); } return left + right ; } }","title":"06: JavaDoc"},{"location":"06_java_docs.html#06-javadoc","text":"Quelle: JavaDoc Cheatsheet Output as PDF: JavaDoc from class Main /** * This is the Main class * @version 1.0.1 * @author Justin Drtvic */ // Main.java public class Main { /** * this is the main function, which is needed to execute the code * @param args params passed by the command line */ public static void main ( String [] args ) { System . out . println ( addition ( 1 , 2 ) ); } /** * addition of two integer numbers * @param left number for left side * @param right number for right side * @return sum of two numbers * @throws IllegalArgumentException for numbers smaller than 0 * @see Math * @see Mathebibel Addition * @since Java API 7 * @deprecated deprecated since 3.0.0 */ public static int addition ( int left , int right ) { if ( left < 0 || right < 0 ) { throw new IllegalArgumentException ( \"we don't like numbers smaller than 0\" ); } return left + right ; } }","title":"06: JavaDoc"}]}; var __search = { index: Promise.resolve(local_index) }
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diff --git a/sitemap.xml b/sitemap.xml
index 3271c63..193ffe2 100644
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